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189 records found
1.
Cabibbo, M., E. Evangelista, et al. (2003). Development of Nano-Structured
1200 and 3103 Aluminum Alloys by Equal Channel Angular Pressing. Thermec'
2003, Leganés, Madrid, Spain, Trans Tech Publications Ltd.
Equal Channel Angular Extrusion (ECAE) has been used to produce
sub-micron-size grain structures in two aluminum alloys (AA1200 and AA3103).
The ECAE was attempted at room temperature and following the so-called route
C. The process via route C involves a 180° angular rotation in between
each pass and it strongly affects the material microstructure by reversing
the shear strain every second pass. Thi sparticular and unique
characteristic of the route C induced a limited buldup of significant
numbers of new high angle boundaries, at least for the first three passes,
which the present proposed paper has been focused to. Three passes by route
C throughout the ECAE die were sufficient to produce a very fine structured
material for both 1200 and 3103 alloys. High resolution EBSP analysis has
been carried out to measure the boundary misorientation within the deformed
structures. Yet the subgrain and grain spacing has been measured revealing a
faster refining effect on the 3103 alloy respect to the 1200 ones.
2.
Cabibbo, M., E. Evangelista, et al. (2004). "Thermal stability study on
two aluminum alloys processed with equal channel angular pressing."
Journal of Materials Science 39(18): 5659-5667.
Equal channel angular pressing was used to produce sub-micrometer size grain
structures in two aluminum alloys (commercially pure 1200 and Al-Mn-Si
3103). ECAP was conducted at room temperature following the process via
"route C," which involves a 180DG angular rotation between passes
and strongly affects material microstructure by reversing the shear strain
every second pass. This unique characteristic of route C induced limited
build-up of new high-angle boundaries, at least for the first three passes.
The equal channel angular pressing was extended to six passes for both
alloys; three passes by route C throughout the die were sufficient to
produce a very fine-structured material for both alloys. High-resolution
electron back-scattered diffraction pattern analysis was carried out to
measure boundary misorientation within the deformed structures. Measurements
of subgrain and grain spacing revealed a more effective microstructure
refining effect in the 3103 than the 1200 alloy. Thermal stability of the
severely deformed materials was studied at temperatures of 130, 240, 330DGC,
corresponding to 0.2, 0.35, 0.5 of the melting temperature. The results
showed considerable grain growth in both materials solely at temperatures
from and above half of the melting one.
3.
Cabibbo, M., E. Evangelista, et al. (2005). "EBSD FEG-SEM, TEM and XRD
techniques applied to grain study of a commercially pure 1200 aluminum
subjected to equal-channel angular-pressing." Micron 36:
401-414.
Microstructural evolution due to equal-channel angular-pressing (ECAP) with
increasingly severe deformation was investigated in a commercially pure 1200
aluminum alloy. A true strain of eight produced sub-micrometer scale grains
and very fine subgrains in the grain interior. The deformation process was
documented and described using field-emission (FEG) gun scanning and
transmission electron microscopy techniques. After eight ECAP passes, the
high-angle grain boundaries accounted for ~70% of all boundaries. The fine
spacing resolution of FEG scanning electron microscopy allowed detailed
grain and subgrain statistical evaluation in the deformed microstructure;
transmission electron microscopic inspection afforded appreciation of the
role of very low-angle misorientation boundaries in the
microstructure-refining process. ECAP results were compared with those
produced by cold rolling. The material’s texture evolved in a
decreasing trend of Cube {001}<100> intensities in favor of Cube
rotated toward the normal-to-pressing direction {001}<120>, while Goss
{110}<001> and {111}<110>, {111}<112>directions slightly
increased with strain.
4.
Cabibbo, M., E. Evangelista, et al. (2005). "Microstructure evolution
of a commercially pure aluminium subjected to severe plastic deformation.
Part II: Texture." Metallurgia Italiana 97(3): 33-36.
Microstructure evolution with increasing severe deformation, via equal
channel angular pressing (ECAP), was investigated in a commercially pure
1200 aluminum. A true strain of 8 was sufficient at producing sub-micrometer
scale grains and very fine subgrains in the grain interior. In a first part
of the study (Part I: Microstructure), the deformation process was
characterised by using microstructure inspection techniques such as TEM and
FEG-SEM (EBSD: electron back-scattered diffraction). In the present
manuscript the evolution of the microstructure induced by the ECAP has been
characterized by using X-ray diffraction techniques. Texture analyses were
performed as a faction of the deformation. The material's texture evolved in
a decreasing trend of cube {001}<100 > intensities in favor of cube
rotated toward the normal-to-pressing direction {001}<120>, whilst
Goss {110}<001> and {111}<110>, {111}<112> directions
slightly increased with strain.
5.
Cabibbo, M., E. Evangelista, et al. (2006). Transmission electron microscopy
study of the strain induced low and high angle boundary development in
equal-channel angular-pressed commercially pure aluminum. 2006 TMS Annual
Meeting, San Antonio, Texas, USA.
Cell and high-angle grain boundary evolution under equal channel angular
pressing (ECAP) was investigated in commercially pure aluminum using
transmission electron microscopy. Transmission electron microscopy
techniques were extensively used to characterize very low-angle (i.e. less
than 1.5 - 2culated b) boundaries, which are difficult, if not impossible,
to detect by field-emission gun scanning electron microscopy with electron
back-scattered diffraction. Boundary misorientation was measured by Kikuchi
pattern and performed across about 120 boundaries at each pass (strain
level). Early, very low-angle boundaries were mostly characterized using
Moire fringes, which yielded a more precise value of lattice angular
misorientation across each boundary. Following route Be to a true strain of
8, the microstructure mainly consisted of nano-scale grains and high-angle
boundaries (misorientations higher than 15 lutions a) accounted for similar
to 70% of all boundaries. The microstructural evolution was compared with
that induced by cold-rolling (CR) to equivalent strains. The substructure
development generally exhibits the same trends, as a function of strain, for
both ECAP and CR and have very similar grain refining potentials.
6.
Cabus, C., H. Regle, et al. (2003). Phases transformation textures in
steels. 2nd International Conference on Thermal Process Modelling and
Computer Simulation, Nancy, France, EDP Sciences, France.
Low-carbon steels used for deep-drawability have properties which depend
greatly on their crystallographic texture. It is therefore important to
control the texture evolution during the thermomechanical processing. Until
recently, little attention has been paid on the understanding of the
textures formation after hot-rolling, which are produced by phase
transformation, although it is recognised that they have an effect on the
development of the texture in the further process (cold rolling and
annealing). Indeed, one of the main difficulties consists in the measurement
of texture above ambient temperature, in the austenite range. In the present
work, EBSD technique is employed on a low-C steel and a method is proposed
to determine local austenite orientation thanks to martensitic one, even if
there is no residual austenite in the steel. The orientation relationships
between the austenite phase and each of its product phases, here martensite
and polygonal ferrite, are analysed and compared. Common Kurdjumov Sachs
variants are detected for both phases. Variations in the intensities of
these variants are also detected and could be due to the different phase
transformation mechanisms, diffusion or shear.
7.
Cahn, R. W. (1990?). "Measurement and Control of Texture."
Metallurgical Reviews: 429-480.
8.
Cai, C., R. I. Chakalova, et al. (2002). "Effect of film thickness on
properties of YBa2Cu3Oycoated on single or
multi-layer oxide buffered biaxially textured nickel tapes." Physica C
372-376: 786-789.
Single Y2O3 or multiple
CeO2/YSZ/CeO2buffer layers, and subsequent YBCO films
with various thicknesses (~70– 1800 nm) are deposited on the cube
textured Ni tapes using pulsed laser ablation.The two types of buffers have
comparable, good biaxial textures, and maintain these features regardless of
the NiO layer which forms and increases during the YBCO deposition. X-ray
Φ-scan FWHM and T c of YBCO films appear to be insensitive to
the change of YBCO thickness and selected buffer.The degradation of local
texture, evidenced by the electron back scatter diffraction in SEM, and the
associated surface roughness may be the reason of Jc dropping as
YBCO thickness increases.
9.
Cai, M. and G. W. Lorimer (2005). "Effect of equal channel angular
extrusion on the microstructures and properties of two extruded Al-Mg-Si
alloys." Journal of Materials Science and Technology 21 (5):
623-629.
The effect of equal channel angular extrusion (ECAE) on the microstructure
of two Al-Mg-Si extrusion alloys was investigated by high resolution
electron backscattered diffraction (EBSD) using a field emission gun
scanning electron microscope (FEG-SEM) and a transmission electron
microscope (TEM). Two contrasting alloys: a dilute alloy, based on alloy
6061 and a concentrated alloy, based on alloy 6069 were employed for this
research. It has been found that prior ECAE to extrusion promotes high angle
grain boundaries (HAGBs) in the extrusions, and the increase in HAGBs ratio
is due to the large shear deformation involved in the process of ECAE.
Tensile testing results show that a further ageing treatment strengthens the
alloys after extrusion and the ECAE processed extrusions are more ductile
than conventional extrusions.
10.
Cain, M. G. and F. F. Lange (1994). "Heteroepitaxy of cubic zirconia on
basal and prismatic planes of sapphire." Journal of Materials Research
9(3): 674-687.
The epitaxial growth of yttria stabilized cubic zirconia produced via the
solution precursor route deposited onto the basal and prismatic planes of
sapphire was characterized. The evolution of the polycrystalline thin film
was described with reference to two concurrent physical processes: abnormal
grain growth due to the growth of grains with preferred orientations and a
morphological instability which resulted in an uncovering of the substrate.
X-ray diffraction, electron backscattering patterns (EBSP), and transmission
electron microscopy (TEM) (plan- and cross-sectional view) were used to
determine the epitaxial relation (normal and in-plane). The observed
epitaxial orientations for the two substrate planes are listed in Table I. A
computer search was used to determine the planar, near coincident site
lattices (NCSL) for the observed normal epitaxial relations(c-plane:
[001]ZrO2 ¦¦ [0001]Al2O3; a-plane:
[001]ZrO2 ¦¦ [1210]Al2O3). The
determined NCSL's did include all the observed epitaxial relations, but also
included others not observed within the same range of misfit and coincident
site density.
11.
Cain, M. G., F. F. Lange, et al. (1995). Substrate and fibre coatings from
aqueous, zirconia-based liquid precursors. Novel Synthesis and Processing of
Ceramics, Institute of Materials: 7-31.
Thin films of cubic zirconia were grown on basal and prismatic lane sapphire
substrates via the liquid precursor route. Highly oriented epitaxial thin
films were produced, their evolution described with reference to two
concurrent physical processes: a morphological instability which resulted in
an uncovering of the substrate coupled with abnormal grain growth of grains
possessing a low interfacial energy with respect to the substrate. The
thermal treatment necessary to initiate abnormal grain growth was dependent
on substrate crystallography. X-ray pi scans recorded the in-plan epitaxial
orientations. Electron back sputtering patterns (EBSP) provided additional
evidence of the in-plane orientations. Cross-sectional and planar view
transmission electron microscopy (TEM) verified some of the orientational
relationships observed in x-ray azimuthal scans and EBSP experiments. A
computer search was used to determine the planar, near-coincident site
lattices (NCSL) for the observed normal epitaxial relations (c-plane:
[001]ZrO2 ||[0001]Al2O3; a-plane: [001]ZrO2
|| [1210]Al2O3). The determined NCSLs did include all the
observed epitaxial relations, but also included others not observed within
the same range of misfit and coincident site density. Application of the
liquid precursor route to fibre coatings for incorporation within
high-temperature ceramic matrix composites was demonstrated where crack-free
films were readily attained using a simple multiple-dip technique.
12.
Caleyo, F., F. Cruz, et al. (1999). "Texture and Grain Size Dependence
of Grain Boundary Character Distribution in Recrystallized Fe-50%Ni."
Scripta Materialia 41(8): 847-853.
13.
Caleyo, F., T. Baudin, et al. (2001). "EBSD Study of the Development of
Cube Recrystallization Texture in Fe-50%Ni." Scripta Materialia
45: 413-420.
14.
Caleyo, F., T. Baudin, et al. (2001). "Orientation correlations in
primary recrystallized Fe-50%Ni." Materials Science and Engineering A
A298(1-2): 227-34.
The correlations between orientations of neighboring grains have been
investigated in a Fe-50%Ni alloy after primary recrystallization and normal
grain growth. Boundary misorientations have been determined by systematic
measurement of individual grain orientations by Electron Back-Scattered
Diffraction (EBSD). It is shown that the recrystallization process in
Fe-50%Ni gives rise to noticeable orientation correlations for
Σ3n and low-angle orientation relationships. Such
correlations result mainly from the non-random spatial distribution of
orientations and from the grain size dependence on orientation developed in
these alloys during recrystallization. In the present alloy, the grain
growth process leads to minor variations in the orientation correlations
associated with low-angle misorientations and reduces considerably those
related to Σ3n orientation relationships.
15.
Caleyo, F., T. Baudin, et al. (2002). "Monte Carlo simulation of
recrystallization in Fe-50%Ni starting from EBSD and bulk texture
measurements." Scripta Materialia 46(12): 829-835.
An improved Monte Carlo approach for simulation of recrystallization from
experimental data is presented. The orientation and stored energy maps
derived by orientation imaging microscopy and the X-ray bulk texture of a
Fe–50%Ni alloy are used as input data. A realistic description of the
dependence of grain boundary properties on misorientation is used to
simulate the nucleation and growth of the new recrystallized grains.
16.
Calonne, V., A. F. Gourgues, et al. (2004). "Fatigue crack propagation
in cast duplex stainless steels: thermal ageing and microstructural
effects." Fatigue & Fracture of Engineering Materials &
Structures 27: 31-43.
17.
Campbell, G. H., M. Kumar, et al. (2003). Effects on grain boundary
constraint on the constitutive response of tantalum bicrystals. Multiscale
Phenomena in Materials - Experiments and Modeling Related to Mechanical
Behavior, San Francisco, CA, United States.
The role of grain boundary constraint in strain localization, slip system
activation, slip transmission, and the concomitant constitutive response was
examined performing a series of uniaxial compression tests on tantalum
bicrystals. Tantalum single crystals were diffusion bonded to form a (011)
twist boundary and compressed along the 011 direction. The resulting
three-dimensional deformation was analyzed via volume reconstruction. With
this technique, both the effective states of stress and strain over the
cross-sectional area could be measured as a function of distance from the
twist boundary, revealing a highly constrained grain boundary region.
Post-test metallurgical characterization was performed using Electron
Back-Scattered-Diffraction (EBSD) maps. The results, a spatial distribution
of slip patterning and mapping of crystal rotation around the
twist-boundary, were analyzed and compared to the known behavior of the
individual single crystals. A rather large area near the grain boundary
revealed no crystal rotation. Instead, patterns of alternating crystal
rotation similar to single crystal experiments were found to be some
distance away (similar to 1mm) from the immediate grain boundary region,
indicating the large length scale of the rotation free region.
18.
Campbell, G. H., S. M. Foiles, et al. (2004). Grain Boundary Structure and
Its Effect on Plasticity. Microscopy and Microanalysis 2004, Savannah,
Georgia, USA, Cambridge University Press.
The behavior of grain boundaries (GB) in a plastically deforming metal has
long been an area of interest to the physical metallurgist. Several
fundamental topics have been considered [1], yet this area of inquiry is
broad enough that many topics have barely been touched upon. Several
fundamental questions can be raised: How does a dislocation interact with a
GB? Will an intersecting dislocation transmit through, become incorporated,
be reflected by, or some combination thereof when interacting with a given
GB? How is this affected by grain boundary structure and defects? How does a
GB change its area? How does a GB slide? How does a GB affect the slip
system activity in its immediate vicinity? How does this affect the work
hardening?
19.
Campos, M. F. d., L. C. R. Lopes, et al. (2005). "Texture and
microtexture studies in different types of cast irons." Materials
Science and Engineering A 398(1-2): 164-170.
Drum and disk brake for trucks are important applications for cast irons. In
the design of these components the low cycle fatigue strength is a critical
attribute for material selection. It is known that fatigue strength is
closely related to microtexture and grain boundary structure. In the present
study, these two significant microstructure factors were evaluated for three
types of cast irons with the aid of a scanning electron microscope equipped
with of electron back scattered diffraction (EBSD) patterns technique.
Samples of grey cast iron, compacted graphite cast iron and nodular cast
iron were extensively studied, and the microstructure, microtexture and
grain boundary misorientation evaluated. Complementarily macrotexture
measurements were performed in X-ray diffractometer with texture goniometer
to determine the orientation texture of the nodular and compacted graphite
cast iron. Differences in the morphologies of pearlite found in those three
types of cast irons are also discussed. The microtexture was evaluated by
means of EBSD. The analysis of texture suggests random distribution of the
orientations of ferrite grains, as a consequence of the process of
production, which includes solidification followed by phase transformation.
The absence of preferential texture is attributed to the inoculation
process, where random nuclei are introduced in the melt. Phase
transformations also favors randomization and this occurs in cast irons
because solidification first gives origin to austenite with subsequent
transformation of austenite into ferrite, after cooling.
20.
Camus, P. P. (2000). Hardware and Software Optimization for Orientation
Mapping and Phase Identification. Electron Backscatter Diffraction in
Materials Science. A. J. Schwartz, M. Kumar and B. L. Adams. New York,
Kluwer Academic/Plenum Publishers: 127-33.
21.
Cao, S. Q., J. X. Zhang, et al. (2005). "Grain boundary character
distribution effects on secondary working embrittlement of interstitial-free
steels." Scripta Materialia 52(1): 25-28.
The effect of grain boundary character distribution (GBCD) on the secondary
working embrittlement (SWE) of interstitial-free (IF) steels has been
evaluated. It is shown that cracks propagation along the high-energy
continuous “random” boundaries results in the SWE and low-energy
boundaries offer obstacles to the propagation.
22.
Cao, S. Q., J. X. Zhang, et al. (2005). "Microtexture, grain boundary
character distribution and secondary working embrittlement of high strength
IF steels." Materials Science and Engineering A 392(1-2):
203-208.
The batch annealing (BA) and continuous annealing (CA) of high strength
interstitial-free (IF) steel sheets have been simulated. Microtexture, grain
boundary character distribution (GBCD) and secondary working embrittlement
(SWE) were investigated using an electron backscatter diffraction (EBSD)
technique. The results show that a crack from SWE occurs preferentially at
random boundaries, that low-angle and low-Σ CSL boundaries can offer
resistance to the propagation of SWE cracks. It is suggested that an optimum
GBCD described as a high frequency of low-angle or low-Σ CSL
boundaries and a more discontinuous random boundary network in the
microstructure of IF steels can offer the potential for decreasing their
ductile-to-brittle transition temperature (DBTT), i.e. reducing their
susceptibility to SWE.
23.
Cao, S. Q., J. X. Zhang, et al. (2006). "Effects of GBCD on cold work
embrittlement of high strength interstitial free steels." Materials and
Design 27(1): 53-57.
The effects of grain boundary character distribution (GBCD) on cold work
embrittlement (CWE) of P-added high strength interstitial-free (IF) steels
have been evaluated using an electron backscatter diffraction (EBSD)
technique. It has been found that cracks propagation along the high-energy
continuous random boundaries resulted in the CWE, and that low-angle or
low-Σ CSL boundaries can offer obstacles to the propagation of cracks.
The results indicate that the CWE of high strength IF steels can be improved
by an optimum GBCD which is described as a high frequency of low-angle or
low-Σ CSL boundaries, and a more discontinuous random boundary
network.
24.
Cao, S., J. Zhang, et al. (2005). "Analysis of orange peel defect in
St14 steel sheet by electron backscattered diffraction (EBSD)." Journal
of Materials Science and Technology 21 (1): 17-20.
In this paper, the orange peel defect in the surface range of the St14 steel
sheet has been investigated using the electron backscattered diffraction
(EBSD) technique. It has been found that the orange peel defect in the St14
steel sheet was resulted from the local coarse grains which were produced
during hot-rolling due to the critical deformation in dual-phase zone.
During deep drawing, the coarse grains with {100}<001> microtexture
can slip on the {112}<111> slip system to form bulging and yields
orange peel defects, while the coarse grains with {112}<110>
orientation do not form the defect as the Schmid factor of {112}<111>
slip system in it equals zero.
25.
Cao, S., J. Zhang, et al. (2005). Effect of local texture on the orange peel
defect in St14 steel sheet. Textures of Materials - ICOTOM 14, Leuven,
Belgium, Trans Tech Publications.
It is often assumed that the texture formation during solid In this paper,
the ‘orange peel’ defect in the surface range of the st14 steel
sheet has been investigated using the electron backscatter diffraction
(EBSD) technique. It has been found that the ‘orange peel’
defect in the st14 steel sheet was resulted from the local coarse grains
which were produced during hot-rolling due to the critical deformation in
dual-phase zone; During deep drawing, the coarse grains with
{100}<001> microtexture can slip on the {112}<111> slip system
to form bulging and yields orange peel defects, while the coarse grains with
{112}<110> orientation do not form the defect as the Schmid factor of
{112}<111> slip system in it equals zero.
26.
Cao, S.-Q., J.-X. Zhang, et al. (2005). "Effect of Grain Boundary
Structure on Secondary Working Embrittlement of IF Steels." Journal of
Iron and Steel Research 17(1): 51-54.
The effect of grain boundary structure on secondary working embrittlement
(SWE) of IF steels was studied by electron back-scatter diffraction (EBSD)
and TEM. The results show that the cracks nucleate at dislocations jamming
at random boundary during deep-draw forming operation, and propagate along
high energy continuous random boundary network, which lead to SWE of IF
steels. Meanwhile, it has also been demonstrated that a crack can be
arrested by low energy boundaries such as low-Z CSL boundaries and low-angle
boundaries.
27.
Cao, W. Q., A. Godfrey, et al. (2003). "Determining dislocation cell
sizes for high-strain deformation microstructures using the EBSP
technique." Journal of Microscopy 211(Pt. 3): 219-229.
The effect of several data collection and processing choices has been
examined for high-resolution electron back-scatter pattern (EBSP)
investigation of a highly deformed sample. The results were compared with a
transmission electron microscope (TEM) investigation of the same sample. The
estimated dislocation cell size was examined as a function of data cleaning
strategy, line intercept vs. reconstruction method, critical misorientation
angle definition and step-size. The best agreement with the TEM results was
obtained using a modified relative reconstruction algorithm on fine
step-size maps allowing some of the noise in the data to be overcome. Step
sizes of up to one-quarter the average cell size yielded similar values for
the estimated average cell size. As a result of the mixture of both high-
and low-angle boundaries, single diffraction condition TEM images may give
larger cell size estimates than the EBSP data. Orientation noise in the EBSP
data, however, still limits the extent to which quantitative information can
be extracted.
28.
Cao, W. Q., A. Godfrey, et al. (2003). "EBSP investigation of
microstructure and texture evolution during equal channel angular pressing
of aluminium." Materials Science and Engineering A 361:
9-14.
Commercial purity aluminum (99.5% Al) was deformed by equal channel angular
pressing (ECAP) using up to 10 passes using route Bc. The evolution of
microstructure and texture was characterized using the electron back
scattered pattern technique. By use of the stereological parameter length
per unit area (LA), it was found that on average a sub-micron grain size is
developed only after 10 passes. Significant heterogeneity exists however in
the sample and in some places a sub-micron grain size is not developed even
after 10 passes. The texture strength was found to increase with increasing
strain over the strain range investigated. Comparison of microstructural
evolution with other deformation modes suggests that ECAP is more similar to
cyclic extrusion-compression than to cold-rolling.
29.
Cao, W. Q., A. Godfrey, et al. (2003). "Annealing behavior of aluminium
deformed by equal channel angular pressing." Materials Letters
57: 3767-3774.
Samples of commercial purity aluminum (99.5%) deformed by equal channel
angular extrusion (ECAE) to accumulated strains of between 1 and 10 were
annealed at different temperatures for a time of 2 h. The microstructural
evolutions of both the deformed and the annealed materials were studied by
electron back-scattered pattern (EBSP) analysis. At high strains the average
cell size is only slowly refined, whilst the average cell boundary
misorientation increases more quickly. Examination of the subgrain
morphology during annealing suggested that whilst for low strains a
recrystallisation occurred in a discontinuous manner, at high strains the
samples showed traits of both discontinuous and continuous annealing
behavior.
30.
Cao, W. Q., A. Godfrey, et al. (2003). "EBSP study of the annealing
behavior of aluminum deformed by equal channel angular processing."
Materials Science and Engineering A 360: 420-425.
Commercial purity aluminum (99.5%) was fabricated by equal channel angular
pressing (ECAP) up to total accumulated strains of approx. 10. The annealing
behavior of material deformed to total strains of approx. 1 and 10 was
investigated, using heat treatments of 2 h at various temperatures from 100
to 500°C. The microstructure of the annealed materials was characterized
using the electron back-scatter pattern technique. A number of parameters
were determined including the distribution and average values of both the
boundary spacings and misorientations. For samples deformed to a total
strain of 1, annealing resulted in discontinuous recrystallization. For
samples deformed to a total strain of 10, annealing resulted in
microstructures exhibiting characteristics of both uniform coarsening and,
in a number of places, of discontinuous recrystallization. An attempt was
made, based on the boundary spacing distributions, to separate these two
components. The grain size after annealing was still however small, being
just 6.4 mm after 2 h at 300°C.
31.
Cao, W. Q., Q. Liu, et al. (2002). Microstructure and Texture Evolution
duing Annealing of an Aluminum ARB Material. ICOTOM 13, Seoul, Korea, Trans
Tech Publications Inc.
Accumulative roll bonding (ARB) has been suggested as one of a number of
methods for producing materials with ultra-fine grain sizes. The annealing
response of material produced my the ARB method at two strains has been
studied over a wide temperature range. Annealed samples were investigated
using the electron back-scatter pattern (EBSP) technique in a scanning
electron microscope equipped with a field emission gun, from which the
texture, microstructure and boundary misorientation angle characteristics
could be determined. Following annealing for 7200 seconds at increasing
temperatures, a gradual microstructural coarsening was observed, whilst in
each case the rolloling texture wsa retained. Hardness measurements on the
samples show a slow decrease in hardness with increasing annealing
temperature. The results of the work suggest that annealing in this material
results in a process of continuous recrystallization
32.
Carbonell, L., P. Ratchev, et al. (2002). "Dry oxidation mechanisms of
copper in trenches." Microelectronic Engineering 64:
63-71.
The effect of trace oxygen on the annealing of Cu/Ta(N) /SiO2/
Si(001) damascene structures was studied. The dry oxidation of copper was
investigated by annealing the wafers at 420°C for 20 min in N ambients
with 2 oxygen concentrations ranging from 0 to 2500 ppm in a Rapid Thermal
Processing (RTP) system. Electron Backscattered Diffraction (EBSD) mapping
(also called ‘Orientation Imaging Microscopy’ (OIM)) and high
resolution Scanning Electron Microscopy (SEM) were used to determine the
structure, texture and chemical composition of the annealed copper. For low
oxygen contents, the oxidation of the surface in bonding areas is initiated
at the grain boundaries and on (111) oriented grains. The oxidation is
selective and depends on the segregation of sulphur at the surface of grains
with a specific orientation. For higher oxygen concentrations, the oxidation
occurs readily and is dependent on the trench geometry, increasing with
decreasing line width. In this case, the dimensions, the distribution of
impurities in the trenches, and the microstructure of the copper modify the
oxidation rate in the small features.
33.
Care, S. and A. Zaoui (1996). "Cavitation at triple nodes in alpha
-zirconium polycrystals." Acta Materialia 44(4):
1323-36.
The damage mechanisms of α-zirconium polycrystals in tension at room
temperature and their dependence on texture and grain size are investigated.
Ductile damage proceeds by growth of cavities appearing at triple nodes; at
larger strain, other cavities nucleate at precipitate platelets. The
cavitation kinetics depend on the tension direction; they are lower the
coarser the grains. For a better understanding of the cavity formation at
triple nodes, the internal stress field due to intergranular plastic
incompatibility is estimated. The mean stress exhibits a logarithmic
singularity on the triple junction. By combining this property with some
experimentally determined features of the cavity growth (tubular shape along
the c axis and growth by activation of prismatic glide), a crystallographic
orientation-dependent cavitation criterion is derived. The determination of
the grains orientation by the E.B.S.D. technique leads to a satisfactory
comparison of the model predictions with the observations.
34.
Carpenter, D. A. and J. S. B. IV (2000). OIM and EDX determination of the
orientation dependence of corrosion in uranium metal. Microbeam Analysis
2000. D. B. Williams and R. Shimizu. Bristol, Institute of Physics
Publishing: 209-10.
35.
Carrere, N., R. Valle, et al. (2004). "Multiscale analysis of the
transverse properties of Ti-based matrix composites reinforced by SiC
fibres: from the grain scale to the macroscopic scale." International
Journal of Plasticity 20: 783-810.
It is well known that the presence of continuous fibres in SiC/Ti composites
leads to a high mechanical anisotropy of the composite between the
longitudinal and the two transverse directions. But it is also possible that
the crystallographic texture of the matrix may lead to a non-negligible
anisotropy of the mechanical properties of the composite. The
crystallographic orientation of the matrix grains was determined using the
Electron BackScattering Diffraction technique. A local texture of the matrix
of the composite is thus evidenced. Finite Element calculations are used to
determine the stress field in the matrix resulting from an applied
transverse loading. The representative mechanical quantities thus determined
are discussed in relation with the fundamental mechanisms of plastic
deformation of the matrix. Finally, the crystallographic texture of the
matrix of the composite is taken into account in the numerical modellings
using a three-scale model that combines crystal plasticity, a
polycrystalline aggregate model and a periodic homogenization through a
Finite Element unit cell for the composite analysis.
36.
Carstensen, J. V., R. K. Ray, et al. (2002). Texture Development in Ni-Co
Alloys Rolled to Moderate Reductions. ICOTOM 13, Seoul, Korea, Trans Tech
Publications Inc.
The texture development during rolling of three Ni-Co alloys, with 31, 41
and 61 wt%Co, has been investigated using electron backscatteing
diffraction. already after 20 and 35% reduction, the textures in the three
alloys are clearly different. The texture development in Ni-30%Co is towards
a copper-type texture, and the texture development in Ni-60%Co is towards a
brass-type texture. In Ni-40%Co the texture development is in between those
in the other two alloys.
37.
Carter, C. B. (1988). "Σ=99 and Σ=41
Grain-Boundaries." Acta Metallurgica 36(10): 2753-2760.
38.
Carter, P., D. C. Cox, et al. (2000). "Process modelling of grain
selection during the solidification of single crystal superalloy
castings." Materials Science and Engineering A 280:
233-246.
which are now used widely for a number of critical applications in gas
turbine engines. The basis of the model is a thermal analysis of the heat
transfer in the vicinity of the chill region onto which the molten metal is
poured. Subsequently the competitive growth of grains during directional
solidification is simulated via a cellular-automaton technique. For the
purpose of model validation, processing trials have been carried out on a
commercial single crystal casting furnace. The thermal cycles set up in and
around the vicinity of the grain selector have been measured, and these are
used to choose a number of critical parameters in the thermal model. The
evolution of grain structure during competitive growth has been
characterised using a number of analytical techniques, including orientation
imaging microscopy. The results are compared critically with the predictions
from the model. It is shown that the model is able to reproduce the
statistical distribution describing the final casting orientation, measured
with respect to the <001> crystallographic pole. The model is used to
study the geometrical factors influencing competitive growth and the
efficacy of two designs of grain selector, and in particular the conferral
of any control of the secondary <001> orientation.
39.
Casey, M., K. Kunze, et al. (1998). "Texture of Solnhofen limestone
deformed to high strains in torsion." Journal of Structural Geology
20(2-3): 255-267.
Soinhofen limestone was deformed in torsion to shear strains (y) ranging
from 1 - 12, at a temperature of 750°C, 300 MPa confining pressure and a
maximum strain rate of 10-3s-1. These deformation
conditions correspond to the intrascrystalline power-law dislocation creep
field close to the boundary to the grain-size-sensitive superplastic creep
field. The grain-shape microstructure was observed using orientation
contrast by backscattered electrons in the SEM. The grains remain sub-equant
with an average grain size of around 4µm, even to the highest strains.
Lattice preferred orientation (LPO) was determined using both X-ray texture
geniometry and automated electron backscatter diffraction (EBSD). The c-axis
preferred orientation develops from two main maxima with a weak sub-maximum,
through two main maxima to a single maximum perpendicular to the shear
plane. The rate of increase of the intensity of the single maximum with
increasing strain diminishes, and it appears that there is a tendency to a
steady-state texture. The final single c-axis maximum is displaced slightly
toward the shortening direction of the applied simple shear. The a-axes tend
to a girdle perpendicular to the c-axis maximum. It is proposed that the
partitioning of deformation between inter- and intra- crystalline mechanisms
results in a pulsating strain rate in the grains, contributing to the
maintenance of sub-equant grains. It is argued that the lattices of
constituent grains rotate continuously with no stable end orientation and
that this can lead to a steady-state texture. The experimental preferred
orientation compares well with that of natural calcite mylonites in the
position of the c-axis maximum and a-axis girdle. Copyright 1998 Elsevier
Science Ltd.
40.
Castellero, A., M. Motyka, et al. (2004). "Synthesis and
crystallisation of
Fe61Co7Zr10Mo5W2B15
bulk metallic glasses." Materials Science and Engineering A
375-377: 250-254.
This paper focuses on the effects of casting temperature and cooling rate on
glass formation of
Fe61Co7Zr10Mo5W2B15.
The presence of the highly stable ZrB2 crystalline phase in the
master alloy allows to obtain a composite (amorphous + ZrB2)
directly by casting the liquid phase from a temperature below the liquidus,
without preventing glass formation. Incomplete dissolution of
ZrB2 causes a reduction of the B content in the amorphous matrix
and, consequently, a shift of crystallisation to lower temperatures and a
change of the mechanism. The effect of cooling rate on glass formation is
clearly visible in a conical bulk sample, where the amorphous fraction
decreases as the sample diameter increases from 1 to 3 mm, because of the
precipitation of bcc-Fe. Furthermore, nanoindentation experiments show
different values of hardness and elastic modulus for the fully amorphous and
composite samples.
41.
Castrofernandez, F. R. and C. M. Sellars (1989). "Relationship Between
Room-Temperature Proof Stress, Dislocation Density and Subgrain Size."
Philosophical Magazine A 60(4): 487-506.
42.
Caton, M. J. and A. H. Rosenberger (2004). Fatigue crack growth variability
in waspaloy under representative loading conditions. Materials Damage
Prognosis - a Symposium of the Materials Science and Technology 2004
Conference, New Orleans, Louisiana, USA.
A key element of a material prognosis system is the ability to predict the
variability in fatigue crack growth rates for given material systems and
loading conditions. This study examines the variability in crack growth
rates in Waspaloy at 650hen the c C under relevant loading frequencies
including the influence of dwell periods. Specimens were taken from
different locations of several forged disks and the grain structures were
characterized. It is observed that grain structure can vary significantly
for different locations within single turbine-engine disks and from disk to
disk. It is also observed that crack growth rates can vary by up to a factor
of 6 for different specimens and that differences are generally more
pronounced under dwell conditions where time dependent mechanisms are
active. The role of grain structure in driving variability in crack growth
rates is difficult to discern using conventional optical microscopy.
However, preliminary results using Orientation Image Mapping (OIM) suggest
significant promise in revealing critical microstructural characteristics
controlling crack growth resistance.
43.
Caul, M. and V. Randle (1996). Grain-boundary characteristics in austenitic
steel. Microscopy and Microanalysis 1996. G. W. Bailey, J. M. Corbett, R. V.
W. Dimlich, J. R. Michael and M. J. Zaluzec. San Francisco, San Francisco
Press: 344-345.
44.
Caul, M. and V. Randle (1997). "Microtexture Analysis of
Interstitial-Free Steel." Materials Characterization 38(3):
155-163.
45.
Celentano, G., E. Varesi, et al. (2003). "Influence of the Substrate
Microstructure on the Superconducting Properties of YBCO Coated
Conductors." IEEE Transactions On Applied Superconductivity
13(2): 2591-2594.
The microstructure of Ni-5at%W (Ni–W) and Ni-11at%V (Ni–V)
biaxially textured substrates has been investigated using X-ray Diffraction
(XRD) and Electron Backscatter Diffraction (EBSD). The correlation between
the substrate microstructure and superconducting transport properties of
YBa2Cu3O7-y/ (YBCO) film grown on it has
been studied on the YBCO/CeO2 Ni–W and YBCO/CeO2
NiO Ni–V architectures. Our study has ascertained that the in-plane
texture of the substrates is one of the most important factors, limiting the
critical current density. The Ni–V substrate has a lower percolation
area due to the larger number of twinned grains and a broader in-plane
angular distribution and, as a consequence, the
YBa2Cu3O7-y /(YBCO) film grown on it has a
critical current density of 0.6 106 A/cm2, depressed
by factor 2 with respect to YBCO grown on the Ni–W substrate. For the
Ni–V substrate, another limiting factor is its low oxidation
resistance. In contrast to Ni–V, the Ni–W substrate has a larger
percolation area, mainly due to the absence of twinned grains, and a high
oxidation resistance.
46.
Celentano, G., V. Galluzzi, et al. (2005). "YBCO films and
CeO2/YSZ/CeO2 buffer layers grown on Ni-Cr-W RABiTS
with a Pd seed layer." IEEE Transactions on Applied Superconductivity
15(2): 2691-2694.
A CeO2/YSZ/CeO2 buffer layer structure was epitaxially
deposited by pulsed laser deposition on a Pd seed layer grown on non
magnetic Ni88Cr8W4 alloy. Structural
analyzes performed by x-ray diffraction and EBSD show a good texture, with
typical YBCO FWHM of about 5 degrees and 8.5 degrees for in-plane and
out-of-plane orientations, respectively. About 300 nm YBCO films deposited
by PLD on such a buffer layer structure, show typical values of critical
temperature of about 89 K and a critical current density greater than 0.6
MA/cm2 at 77 K and self field.
47.
Celik, E., Y. Akin, et al. (2004). "Fabrication of
La2Zr2O7 buffer layers on Ni tapes by
reel-to-reel sol–gel technique." Materials Science and
Engineering B 106: 182-190.
In order to investigate the optimal conditions for highly orientated and
epitaxial buffer layers on textured Ni tapes, we have deposited perovskite
textured La2Zr2O7 (LZO) films on Ni tapes
using a reel-to-reel sol–gel process for fabrication of second
generation high-Tc superconductors. Of these usual parameters, precursor
types, solvents, chelating agents, and annealing conditions were chosen to
prepare LZO solutions. This effect on epitaxial growth of LZO of these
processing and texturing parameters was evaluated using X-ray diffraction
(XRD), environment scanning electron microscopy (ESEM), energy dispersive
spectrometry (EDS) and orientation imaging microscope (OIM), atomic force
microscope (AFM) and X-ray pole figure analysis. Based on the following
results, we have found textured, homogenous, dense, crack free and pinhole
free, LZO films with a strong c-axis orientation on textured Ni tapes by
post-annealing at 1150°C for 10 min under 4% H2–Ar gas
flow.
48.
Celotto, S., R. C. Pond, et al. (2004). "In situ SEM-EBSD observations
of the hcp to bcc phase transformation in commercially pure titanium."
Acta Materialia 52(4): 821-832.
This study presents in situ observations of the hcp (α) to bcc (β)
phase transformation in commercially pure titanium at 882. Using t C using
SEM imaging concurrent with crystal orientation determination using EBSD
Direct observations of the onset of the phase transformation are presented
showing the early stages of the growth of β plates within α grains
and allotriomorphic β along α-α grain boundaries.
Intragranular β plates have a Burgers orientation relationship (OR)
with the parent α grain and are lenticular in shape. These plates also
have a tent surface relief and surface-traces consistent with habit planes
predicted by the phenomenological theory of martensitic crystallography for
pure titanium. These features suggest a military component to the growth
mechanism. The β allotriomorphs have a Burgers OR with one of the
α grains abutting at the boundary, but do not have surface relief
characteristic of a military transformation. These are likely to grow by a
civilian mechanism. The final stage of the transformation is a process of
competitive growth of the two β forms, with the allotriomorphic β
dominating by virtue of its faster moving α-β interfaces. Grain
growth in the β stability field is more than an order of magnitude
faster than that in the α field at temperatures near the phase
transformation. Copyright 2003 Published by Elsevier Ltd on behalf of Acta
Materialia Inc.
49.
Cerchiara, R. R., P. E. Fischione, et al. (2003). Recent developments in
automated sample preparation for FESEM. Conference Proceedings of the 29th
International Symposium for Testing and Failure Analysis, Santa Clara,
California, USA, ASM International.
Standard analytical practice in the semiconductor industry depends on fast,
efficient and reliable sample preparation prior to FESEM. "In
lens" imaging technology and orientation mapping (EBSD) demand sample
surfaces free of physical damage and residual contamination. An integrated
preparation tool has been developed that incorporates the functionality
necessary for argon oxygen plasma cleaning, ion beam etching (IBE), reactive
ion beam etching (RIBE), reactive ion etching (RIE), and ion beam sputter
coating (IBSC). Control, monitoring and sequential automation of the
processes is accomplished through a novel combination of software and
hardware. FESEM results for Al and Cu based microelectronic materials will
be discussed, as well as EBSD results for bulk metals. Improvements in
throughput and subsequent materials characterization will be
demonstrated.
50.
Chai, K. H., Y. S. Choi, et al. (2002). Effects of Sulfur Segregation on
Selective Grain Growth and Final Texture in Thin Gauged Grain-Oriented 3%
Silicon Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Correlation between sulfur segregation, surface-energy-induced selective
growth and final texture has been investigated in 100µm thick
grain-oriented 3% silicon steel. During final annealing under a vacuum or
hydrogen atmosphere at 1200°C, sulfur segregates to the free surface and
grain boundaries, and a convex profile is due to the loss of segregated
sulfur by the evaporation or the H2S reaction, which forms a
sulfur-depleted zone just below the strip surface. The surface-segregated
sulfur induces a surface energy difference among crystal planes and causes a
strong suppression of grain boundary movement. The annealing texture was
changed from {111}<001> to {100}<uvw> and subsequently to
{111}<uvw>, with increasing surface-segregated sulfur concentration.
The surface-energy-induced selective growth of surviving Goss grains was
observed within a segregated-sulfur free time range. After final annealing,
the strip showed a strong Goss texture, resulting in high magnetic induction
(B10) of about 1.9 Tesla.
51.
Chakravartty, J. K., M. K. Asundi, et al. (1983). "Dynamic Strain-Aging
of A203D Nuclear Structural-Steel." Journal of Nuclear Materials
119(1): 51-58.
52.
Chandrasekaran, D. and M. Nygaards (2003). "A study of the surface
deformation behaviour at grain boundaries in an ultra-low-carbon
steel." Acta Materialia 51(18): 5375-5384.
Tensile specimens of ultra-low-carbon ferritic steel with two different
grain sizes were studied by atomic force microscopy (AFM) and electron
backscatter diffraction (EBSD) after different plastic strains up to 10
percent. Different parameters, such as the change in surface roughness and
the change in misorientation with strain, were evaluated. There was good
agreement between the AFM and EBSD results. Both the surface roughness and
the misorientation measurements on the surface showed a linear increase with
the overall strain, an obvious consequence being that both AFM and EBSD are
suitable for characterising the surface deformation behaviour. The results
are discussed with respect to the difference in grain size in the samples
and the implication on the strain hardening behaviour.
53.
Chang, C. P., P. W. Kao, et al. (2004). "High angle boundary formation
by grain subdivision in equal channel angular extrusion." Scripta
Materialia 51(6): 565-570.
Intensive work on transmission electron microscope (TEM) was carried out to
clarify high angle boundary (HAB) formation during equal channel angular
extrusion (ECAE). It was demonstrated that newly developed HABs are mainly
formed by the occurrence of grain subdivision, and the occurrence of grain
subdivision is strongly influenced by the original grain orientations and
ECAE strain path. Copyright 2004 Acta Materialia Inc. Published by Elsevier
Ltd. All rights reserved.
54.
Chang, C. S. T., A. S. C. Yeung, et al. (2005). Producing a Random
Recrystallization Texture in 6111 Aluminum Alloy. Textures of Materials -
ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
6111 Aluminium Alloy in the hot band state was cold rolled to 80% was then
annealed at 450°C, 500°C and 540°C for recrystallization. The
hot band was also solution heat treated, cold rolled and annealed to the
same temperature to look at the difference in the recrystallization texture
and precipitation states. It was found that the samples which were cold
rolled and annealed without solution heat treatment gave Goss and P
components after annealing. For the samples with solution heat treatment,
the 450°C sample has a retained Cu type rolling texture while for the
500°C and 540°C the textures are quite random. The retained rolling
texture found in the 450°C sample is due to the fact that it was
partially recrystallized as the precipitates prevent complete
recrystallization. The difference in the precipitation states during and
after annealing of the samples with and without solution heat treatment
affects the final recrystallization texture.
55.
Chang, C. S. T., H. Inagaki, et al. (2003). Reducing Cube Volume in
Recrystallized Texture by Controlling the Finishing Temperature and rolling
Strain in Al-5%Mg Alloy. Thermec' 2003, Leganés, Madrid, Spain, Trans
Tech Publications Ltd.
A research program aimed at producing weak texture in a strong work
hardening alloy, Al-5%Mg has been undertaken. Two strategies are reported.
In the first, the effect of hot band finishing temperature is investigated.
When the temperature was high enough to produce a recrystallized hot band,
subsequent cold rolling and annealing at 300°C produced a weaker texture
compared with annealing at 450°C. A second approach involved splitting
the rolling process into two parts with an intermediate anneal, with both
the the intermediate and final annealing temperatures as variables. The best
results were obtained when the intermediate anneaing temperature produced a
grain size of 35µm compared with the lower temperature of grain size
10µm, and the final annealing temperature was low.
56.
Chang, L. and H.-G. Chen (2005). "Diamond nucleation on
Ni3Al substrate using bias enhanced nucleation method."
Diamond and Related Materials 14(2): 183-191.
Diamond deposition with positive and negative bias enhanced nucleation (BEN)
pretreatments on mirror-polished polycrystalline Ni3Al substrates
has been investigated, respectively. It was found that diamond deposition on
the substrates under both biasing exhibited significant variations among
grains of different orientations. The substrate surface was found to be
rough in the case of negative biasing, whereas it was smooth in the case of
positive biasing. Thus, the correlation of the crystallographic orientation
of grains on the samples with the diamond nucleation behavior was
systematically characterized for the case of positive biasing by electron
backscattered diffraction method with scanning electron microscopy. Diamond
deposition on Ni3Al grains near (111) orientation results in
higher nucleation densities, while the densities are low on (110) and (100)
oriented grains. Also, the interfacial microstructure between diamond
deposited and Ni3Al was characterized by cross-sectional
transmission electron microscopy. Copyright 2004 Elsevier B.V. All rights
reserved.
57.
Chang, Y. A. (2006). "Phase Diagram Calculations in Teaching, Research
& Industry." Metallurgical and Materials Transactions A
37A(2): 273-305.
58.
Chang, Y. J., J. Jang, et al. (2004). "Electron backscattered
diffraction study of poly-Si by Ni-mediated crystallization of amorphous
silicon using a SiO2 nanocap." Journal of Vacuum Science and
Technology A 22(3): 650-654.
The crystalline orientation of the disk-shaped grains in poly-Si produced by
Ni-mediated crystallization of a-Si using a SiO2 nanocap was
studied using electron backscattered diffraction measurements. A layer of
SiO2 was formed on the nanocap by O2 plasma treatment
on a-Si. The SiO2 nanocap was heated in a UV scan system to
induce crystallization. It was observed that NiSi2 crystallites
were formed when Ni atoms in a-Si duffused through the nanocap. The results
showed a growth in disk-shaped grains in poly-Si which was approximately
from 6 to 20µm and a change in thickness of nanocap on a-Si from 2.4
to 3.2nm. (Edited abstract)
59.
Chapelle, D. and M. Darrieulat (2003). "The occurence of shear banding
in a millimeter scale (123)[634] grain of an Al-4.5% Mg alloy during plane
strain compression." Materials Science and Engineering A
347(1-2): 32-41.
The appearance of localization in shear bands during plane strain
compression (PSC) of an Al-4.5% Mg alloy is investigated, with emphasis on a
millimeter scale S-orientated grain in the logitudinal section of the
specimen, upon which a gold microgrid was deposited. In order to justify
this focus, attention is also paid on smaller grains of other areas. The
microgrid technique allows the strain field at various steps of deformation
to be followed and in-plane components to be plotted over the selected
region. Electron back scattered diffraction analysis was also used to gain
an insight into the crystallography of local lattice rotations. One can then
predict the potentially activated slip systems according to the Scmid law
with Taylor's hypothesis, and assert the initial crystallographic feature of
shear banding. This provides the opportunity to gain a more complete
understanding, assuming a grain scale efect, of the mechanisms involved in
the occurrence of shear banding in this alloy, and to reveal its influence
on the rolling texture.
60.
Charit, I. and R. S. Mishra (2004). "Evaluation of microstructure and
superplasticity in friction stir processed 5083 Al alloy." Journal of
Materials Research 19(11): 3329-3342.
Friction stir processing (FSP) has been developed as a potential grain
refinement technique. In the current study, a commercial 5083 Al alloy was
friction stir processed with three combinations of FSP processing
parameters. Fine-grained microstructures with average grain sizes of 3.5-8.5
µm were obtained. Tensile tests revealed that the maximum ductility of
590% was achieved at a strain rate of 3 ×
10-3s-1 and 530 °C in the 6.5-µm grain size
FSP material, whereas for the material with 8.5-µm grain size, maximum
ductility of 575% was achieved at a strain rate of 3 ×
10-4s-1 and 490 °C. The deformation mechanisms for
both the materials were grain boundary sliding (m ~0.5). However, the
3.5-µm grain size material showed maximum ductility of 315% at
10-2s-1 and 430 °C. The flow mechanism was
solute-drag dislocation glide (m ~0.33). This study indicated that
establishing a processing window is crucial for obtaining optimized
microstructure for optimum superplasticity.
61.
Charrier, J. and J. DeFouquet (1980). "Application of Bergstrom Model
to Analysis of Evolution of Athermal Component of Alpha-Titanium Traction
Stress." Materials Science and Engineering 46(1):
121-123.
62.
Chastel, Y., L. Delannay, et al. (2003). "Measurement of In-Grain
Orientation Gradients by EBSD and Comparison with Finite Element
Results." Advanced Engineering Materials 5(8): 597-600.
The characterization of In-grain orientation gradients by electron
backscattering diffraction (EBSD) technique was studied. The study, based on
finite element (FE) technique, involved the simulation of plane strain
compression of the crystal grains. In regard to it, the construction of
orientation distribution function (ODF) by superimposing spherical Gaussian
distributions on the mean orientation of grains was also discussed. (Edited
abstract)
63.
Chateigner, D., G. Camana, et al. (2002). Textural Analysis of a
Microcrystalline Quartz using X-Ray and Electron Backscatter Diffraction
(EBSD) Techniques. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
An unusual microcrystalline quartz texture has been recognized in the
investigation of pervasively silicified ore-bearing horizons occurring in
the uppermost part of carbonate platform sequences of different ages (from
Precambrian to Mesozoic) and of different geotectonic settings. This
peculiar texture has been labeled "grid-work texture", and derives
only by a rather fast and preferred crystallization of quartz on the
pre-existing morphological faces of other developed quartz crystals. The 001
pole figures obtained by X-ray textural analysis describe this grid-work
texture as constituted by two components of orientation: one component at
about 35° degrees from the normal to the surface of the sample and a
second orientation component having the c axes oriented at about 75°
from the normal to the surface of the sample. Textural maps and parameters
obtained by EBSD found very similar components of orientation highlighting
as 30 - 40° and 70-80° misorientations are very common; moreover
they allowed to establish as many of the quartz crystals are characterized
by Dauphiné Twin boundaries.
64.
Chatterjee, S., D. Bhattacharjee, et al. (2003). "Variation in
structure and magnetic properties during decarb-annealing of electrical
steel." Scripta Materialia 49: 355-360.
Laminations punched out from semi-processed cold rolled non-oriented
electrical steel sheets undergo decarbannealing (DA) treatment. Changes in
microstructure and texture during this treatment have been investigated
under laboratory conditions. It has been observed that development of
unfavorable texture during grain growth can negate the beneficial effects of
the DA.
65.
Chaturvedi, M. C. and D. L. Chen (2004). "Effect of specimen
orientation and welding on the fracture and fatigue properties of 2195
Al–Li alloy." Materials Science and Engineering A 387-389
: 465-469.
In view of the use of 2195 Al–Li alloy in the construction of
super-light-weight external fuel tank of space shuttles, bulkheads of
reusable single-stage-to-orbit launch vehicles and in combat ground
vehicles, the dependence of tensile properties, fracture toughness and
fatigue resistance of this alloy on the specimen orientation and welding is
very important and was studied. The T8 base alloy, with primary
strengthening precipitates of T1(Al2CuLi) phase,
contained mainly brass-type texture. After welding with AA 4043 filler
alloy, the fusion zone (FZ) consisted of T (AlLiSi) phase and in the
heat-affected zone (HAZ) T1 phase was replaced by TB
(Al7Cu4Li) phase, and micro-cracks were observed. The
post-weld heat treatment (PWHT) resulted in the spheroidization of primary T
phase and the precipitation of more T particles in the FZ, and the
dissolution of TB phase and the re-precipitation of
T1phase in the HAZ. The yield strength, fracture toughness and
fatigue threshold of the 2195-T8 alloy was observed to depend on the
specimen orientation, with the lowest values obtained at 45° to the
rolling direction. Welding resulted in a reduction in the tensile properties
and fatigue strength. The post-weld heat treatment enhanced the yield
strength, but no increase in fatigue strength was observed. Fracture
mechanisms in various cases were evaluated by SEM examination of fracture
surfaces and are discussed.
66.
Chaubet, D., B. Bacroix, et al. (2002). An EBSD Study of Static
Recrystallization of Cold-Rolled Zircaloy-4 Sheets. ICOTOM 13, Seoul, Korea,
Trans Tech Publications Inc.
Recovery and recrystallization of zircaloy-4 initially cold-rolled at 80%
thickness reduction are studied. Deformed specimen underwent interrupted
annealing treatments of 30 minutes at temperatures varying from 500 to
600°C. Evolution of microstructure is followed using micro-hardness
measurements, X-ray diffraction and orientation imaging. It has been shown
that both recovery and classical recrystallization occur in zircalloy-4.
Recovery is associated to areas where the <c> axes are close to the
normal direction. The classical recrystallization component (0001)
<1120> is aleady present in the deformed and recovered states. Its
growth during annealing is mainly observed in areas where orientation
variations are large, and EBSD quality factor vey low. The orientations of
the new grains shoe some spread of <c> axis from ND.
67.
Chaudhuri, J., J. H. Edgar, et al. (2005). Oxidation of aluminum nitride for
defect characterization. 2005 Materials Research Society Fall Meeting,
Boston, Massachusetts, USA.
The thermal oxidation of aluminum nitride was developed as a means to study
defects in bulk aluminum nitride crystals. The oxidation kinetics was
established for the dry oxidation of highly textured AlN polycrystals
produced by sublimation-recombination crystal growth in a tungsten furnace.
Despite seeding on polycrystalline tungsten, the grains were predominantly
0001 oriented as verified by electron backscattering diffraction (EBSD). The
oxidation rate is dependent on the crystal's orientation, polarity, stress,
and surface condition, thus oxidation decorates grain boundaries, polishing
scratches, and inversion domains by producing oxide layers of different
thicknesses. Low temperature (800ng to the C) dry oxidation produced an
amorphous oxide layer and generated a high density of defects (vacancies,
stacking faults, and dislocations) in the nitride near the oxide/nitride
interface, as observed by cross-sectional transmission electron microscopy.
In contrast, high temperature oxidation (1000s.uously C) produced a
crystalline oxide layer, and left the nitride free of observable
defects.
68.
Chauvy, C., P. Barbéris, et al. (2004). Dynamic Recrystallization of
Zircaloy-4 during Working within the Upper α-Range. Second Joint
International Conference on Recrystallization and Grain Growth, ReX &
GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
Compression tests were used to simulate simple deformation paths within the
upper α-range of Zircaloy-4 (i.e. 500°C-750°C). The mechanical
behaviour reveals two different domains: at low temperatures and large
strain rates, strain hardening takes place before flow softening, whereas
this first stage disappears at lower flow stress levels. Strain rate
sensitivity and activation energy were determined for both domains. Dynamic
recrystallization was investigated using the Electron Backscattering
Diffraction (EBSD) technique. It appears that the mechanism involved here is
continuous dynamic recrystallization (CDRX), based on the increasing
misorientation of subgrain boundaries and their progressive transformation
into large angle boundaries. At low strains (ε is less than or equal
to 0.3), CDRX kinetics are similar whatever the deformation conditions,
while higher temperatures and lower strain rates promote recrystallization
at large strains.
69.
Che, H., Y. Wang, et al. (2004). "Advances in Microscale Laser Shock
Peening." Tsinghua Science and Technology 9(5): 506-518.
The response of materials after microscale laser shock peening (mu LSP) was
experimentally characterized and compared with the theoretical prediction
from the finite element method (FEM) analysis in microlength level. X-ray
micro-diffraction technique was applied to the post-peened single crystal
aluminum of (001) and (110) orientations, and X-ray profile was analyzed by
sub-profiling and Fourier analysis method. Spatially resolved residual
stress and strain deviation was quantified and explained in terms of the
hetero-geneous dislocation cell structure. In-plane crystal lattice rotation
induced by pLSP was measured by elec-tron backscatter diffraction (EBSD) and
compared with the FEM simulation. Average mosaic size was evaluated from
X-ray profile Fourier analysis and compared with the result from EBSD
Surface strength in-crease and dislocation cell structure formation were
studied. The systematical characterization will lay the ground work for
better understanding the effect of mu LSP in microlength level and
developing more realistic simulations.
70.
Chen, D. L., M. C. Chaturvedi, et al. (1999). "Fatigue crack growth
behavior of X2095 Al–Li alloy." International Journal of Fatigue
21: 1079-1086.
Microstructures and micro-textures of X2095 Al–Li alloy in
as-received/superplastic state were characterized by means of SEM/BDS, X-ray
diffraction and orientation imaging microscopy (OIM). It was observed that
the microstructure of the alloy was typical of a particulate-reinforced
composite material, consisting of aluminum matrix and homogeneously
distributed TB(Al7Cu4Li) particles with a volume fraction of about 10%.
Brass-type texture was the dominant texture component. Both constant
amplitude and near-threshold fatigue crack growth rates of the alloy in the
L–T and T–L orientations were determined at different stress
ratios. Particular attention was paid to the role of the TB phase in the
fatigue crack growth. When a fatigue crack approached a TB particle, the
crack basically meandered to avoid the particle. The TB particles thus
provided a strong resistance to the propagation of fatigue crack by
promoting crack deflection and the related crack closure effects. The
fatigue crack propagation behavior has been explained by the microstructural
features, micro-textures, cracking characteristics and crack closure
effects.
71.
Chen, H., J. W. Kysar, et al. (2004). "Characterization of plastic
deformation induced by microscale laser shock peening." Journal of
Applied Mechanics 71(5): 713-723.
Electron backscatter diffraction (EBSD) is used to investigate crystal
lattice rotation caused by plastic deformation during high-strain rate laser
shock peening in single crystal aluminum and copper sample on (110) and
(001) surfaces. New experimental methodologies are employed which enable
measurement of the in-plane lattice rotation under approximate plane-strain
conditions. Crystal lattice rotation on and below the microscale laser shock
peened sample surface was measured and compared with the simulation result
obtained from FEM analysis, which account for single crystal plasticity. The
lattice rotation measurements directly complement measurements of residual
strain/stress with X-ray micro-diffraction using synchrotron light source
and it also gives an indication of the extent of the plastic deformation
induced by the microscale laser shock peening.
72.
Chen, H., Y. L. Yao, et al. (2005). "Fourier analysis of X-ray
micro-diffraction profiles to characterize laser shock peened metals."
International Journal of Solids and Structures 42 (11-12):
3471-3485.
X-ray micro-diffraction profiles using a synchrotron light source were
analyzed via Fourier transformation for single crystal Aluminum and Copper
samples subjected to micro-scale laser shock peening. Specifically, the
asymmetric and broadened diffraction profiles registered across the shock
peen region were observed and analyzed by classic Warren and Averbach (W-A)
method ÝWarren, B.E., Averbach, B.L., 1950. The effect of cold-work
distortion on X-ray patterns. Journal of Applied Physics 21, 595-599¨
and modified W-A method ÝUngar, T., Borbely, A., 1996. The effect of
dislocation contrast on X-ray line broadening: A new approach to line
profile analysis. Applied Physics Letters 69, 3173-3175¨. Average strain
deviation, mosaic size and dislocation density were estimated for the first
time with a spatial resolution of 5 mu m. The results compare well with the
simulation results obtained from FEM analysis and from electron backscatter
diffraction (EBSD) measurements. Differences in response caused by different
materials and crystalline orientations (1 10 and 001) were also
studied.
73.
Chen, H., Y. Wang, et al. (2004). "Systematical characterization of
material response to microscale laser shock peening." Journal of
Manufacturing Science and Engineering 126(4): 740-749.
The response of materials after microscale laser shock peening (pLSP) was
experimentally characterized and compared with the theoretical prediction
from FEM analysis in microlength level. Since 1aLSP is predominantly a
mechanical process instead of a thermal process, the characterization
focuses on mechanical properties and associated microstructures. An X-ray
microdiffraction technique was applied on the postpeened single crystal
aluminum of (001) and (110) orientations, and an X-ray profile was analyzed
by subprofiling and Fourier analysis method. Spatially resolved residual
stress and strain deviation was quantified and explained in terms of the
heterogeneous dislocation cell structure. In-plane crystal lattice rotation
induced by mLSP were measured by electron backscatter diffraction (EBSD) and
compared with the FEM simulation. Average mosaic size was evaluated from
X-ray profile Fourier analysis and compared with the result from EBSD
Surface strength increase and dislocation cell structure formation were
studied. The systematical characterization helps develop more realistic
simulation models and obtain better understanding in microlength level.
74.
Chen, H.-G. and L. Chang (2005). "Diamond nucleation on
Ni3Al substrate using bias enhanced nucleation method."
Diamond and Related Materials 14(2): 183-191.
Diamond deposition with positive and negative bias enhanced nucleation (BEN)
pretreatments on mirror-polished polycrystalline Ni3Al substrates
has been investigated, respectively. It was found that diamond deposition on
the substrates under both biasing exhibited significant variations among
grains of different orientations. The substrate surface was found to be
rough in the case of negative biasing, whereas it was smooth in the case of
positive biasing. Thus, the correlation of the crystallographic orientation
of grains on the samples with the diamond nucleation behavior was
systematically characterized for the case of positive biasing by electron
backscattered diffraction method with scanning electron microscopy. Diamond
deposition on Ni3Al grains near (111) orientation results in
higher nucleation densities, while the densities are low on (110) and (100)
oriented grains. Also, the interfacial microstructure between diamond
deposited and Ni3Al was characterized by cross-sectional
transmission electron microscopy.
75.
Chen, H.-L., B. S. El-Dasher, et al. (2006). "Surface deformation
behavior of beta solution treated and overaged Ti-6Al-4V during laser shock
processing." Journal of Applied Physics 99(10).
The surface of a beta solution treated and overaged Ti-6Al-4V alloy specimen
deformed by laser shock processing was studied using electron backscatter
diffraction, scanning electron microscopy, and atomic force microscopy. Slip
steps were observed within grains oriented with their c axis nearly parallel
to the specimen surface normal. Based on the slip step traces and
orientation information, the slip planes were determined to be [11
2õ2] for grains with their c axis within 15° of the specimen
surface normal and [11 2õ1] for grains with their c axis between 15
° and 40° away from the specimen surface normal. Although both these
planes are known to belong to twinning systems, [11 2 õ2] <11
2õ3õ> and [11 2õ1] <11 2õ6õ>,
respectively, the latter has not been observed to operate as a slip system.
Examination of the Taylor factors associated with these slip systems shows
that the grains with slip steps have the lowest Taylor factors.
Determination of localized lattice rotations showed a unique behavior in
grains with slip steps, such that all the lattice rotations were
concentrated about the steps, with almost no orientation variations in
between slip steps. This distribution indicates that stress concentrations
exist at the slip steps, which could potentially affect the performance of
the material.
76.
Chen, H.-W. and V. Rudolph (2002). The 3-D structure of polycrystalline
diamond film by electron backscattering diffraction (EBSD). Eighth
International Conference on New Diamond Science and Technology, Melbourne,
Vic., Australia, Elsevier.
A lithographic method was used to produce polycrystalline diamond films
having highly defined surface geometry, showing an array of diamond tips for
possible application as a field emitter device. The film grown in this study
used microwave plasma assisted chemical vapour deposition (MACVD) on a
silicon substrate; the substrate was then dissolved away to reveal the
surface features on the diamond film. It is possible to align the
crystallite direction and affect the electron emission properties using a
voltage bias to enhance the nucleation process and influence the nuclei to a
preferred orientation. This study focuses on the identification of the
distribution of crystal directions in the film, using electron
backscattering diffraction (EBSD) to identify the crystallographic character
of the film surface. EBSD allows direct examination of the individual
diamond grains, grain boundaries and the crystal orientation of each
individual crystallite. The EBSD maps of the bottom (nucleation side) of the
films, following which a layer of film is ion-milled away and the mapping
process repeated. The method demonstrates experimentally that oriented
nucleation occurs and the thin sections allow the crystal texture to be
reconstructed in 3-D.
77.
Chen, J., T. Sekiguch, et al. (2005). "Electron-beam-induced current
study of small-angle grain boundaries in multicrystalline silicon."
Scripta Materialia 52: 1211-1215.
Recombination activity of small-angle grain boundaries (SA GBs) in
multicrystalline silicon (mc-Si) was studied by means of
electron-beam-induced current (EBIC) technique. In the as-grown mc-Si, the
EBIC contrasts of special R and random GBs were weak at both 300 and 100 K,
whereas those of SA GBs were weak (<3%) at 300 K and strong
(30–40%) at 100 K. In the contaminated mc-Si, SA GBs showed stronger
EBIC contrast than R and R GBs at 300 K. It is indicated that SA GBs possess
high density of shallow levels and are easily contaminated with Fe compared
to other GBs.
78.
Chen, J., Z. Fan, et al. (2005). "The standard guideline for electron
backscattered diffraction analysis." Chinese Journal of Stereology and
Image Analysis 10(4): 250-252.
This paper briefly introduces the national organization and the
International Organization for Standardization (ISO) on Microbeam Analysis.
The natioanl standard Guideline for Electron Backscattered Diffraction
Analysis (GB/T19501-2004) is also recommended as well as the working draft
of the future international standard Guideline for Electron Backscattered
Diffraction Analysis (ISO/WD 24173) which is based on this national standard
and was formally permitted to carry on by ISO in 2005.
79.
Chen, L. and D. Casasent (1998). Effective approach for detecting bands of
EBSP with Hough transform. SPIE The International Society for Optical
Engineering, Bellingham, WA, USA., SPIE.
An effective approach for the detection of the electron backscatter
diffraction patterns (EBSPs) with the Hough transform has been described in
this paper. Based on the peak-finding method and the enhancement filter in
the Hough space, this approach can give automatically the orientations,
widths and coordinates of the central intersection points of the bands in
the patterns. Comparison with other Hough approaches shows that our approach
is more robust for the very low quality patterns and has an advantage of low
time cost. No further fitting scheme or constrain conditions are needed to
get correct bands. Results have been presented. (Author abstract)
[References: 10]
80.
Chen, L., H.-P. Feng, et al. (2006). "Macro-texture and micro-twins in
free-standing diamond films." Journal of Inorganic Materials
31(1): 239-244.
The techniques of orientation mapping based on electron back-scattering
diffraction, scanning electron microscopy and X ray diffraction were used to
investigate macro-texture, microstructure and orientation evolution of
grains. The preparation atmosphere with lower purity is one of the important
reasons, which induces twins in large quantity in the diamond films
investigated. The impurity atoms reduce the stack fault energy in diamond,
lower the obstacles to the formation of twin boundaries, and therefore
accelerate the appearance of twins. Frequent twining results in the texture
transformation from [100] to [122], a weakened film texture as well as the
tendency leading to isotropic properties. The [110] oriented grains keep
their orientation after twinning, and therefore indicate certain orientation
stability against the repeatedly twinning effects.
81.
Chen, L., M. C. Simmonds, et al. (2001). "Crystal orientation effects
on sputtering and depth resolution in GDOES." Surface and Interface
Analysis 31: 206-211.
We investigate crystal orientation effects in the sputtering rate of pure
iron in glow discharge optical emission spectrometry (GDOES). Scanning
electron microscopy (SEM), optical profilometry and electron backscattered
diffraction (EBSD) are used to investigate details of the surface structure
and to correlate the depth of burn—and hence sputtering
rate—with the crystallography of the sample. The microstructure of the
sputtered crater bottom is classified into three types: ‘rough’,
‘concaved’ and ‘smooth’. It was found that there is
a correlation between the crystal orientation normal to the surface, the
resulting surface texture and the sputtering rate: ‘rough’
texture results from a crystallographic pole of [111] normal to the surface;
‘concaved’ texture is close to [001]; and ‘smooth’
tends to be between [111] and [001]. It was found that the average sputtered
depth of the micro-areas close to [001] pole is deeper than that of those
close to [111]. Implications for the depth resolution in GDOES are
discussed.
82.
Chen, L., W. Mao, et al. (2004). "Experimental determination and
theoretical prediction of twin orientations in magnesium alloy AZ31."
Scripta Materialia 50(8): 1163-1168.
Twin orientations in channel die compression tests were determined by means
of X-ray diffraction and EBSD technique in two samples of magnesium alloy
AZ31 with different initial textures. The measured orientations are compared
with those calculated from different twin variants and initial orientations.
To elucidate the measured results, twin strain tensor of each twin variant
was also computed. It is demonstrated that the twin variant, which leads to
the basal orientation, fitted the externally imposed strain tensor best and
was activated at first. The texture evolution is discussed in terms of the
competition between twinning and prismatic slip.
83.
Chen, N., S. Zaefferer, et al. (2002). Abnormal Grain Growth in Silicon
Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Grain growth during secondary recrystallization of polycrystalline materials
is controlled by driving force and grain boundary mobility. Experiments and
simulations have been carried out to sort out which of these effects are
responsible for the development of the sharp Goss texture during secondary
recrystallization of Si-steel. The influence of surface energy and chemical
composition difference as driving force for abnormal Goss grain growth has
been investigated by EBSD measurements. In modeling of abnormal grain growth
by Monte Carlo method, mobility of CSL grain boundaries and high energy
grain boundaries have been checked using EBSD measurement results as initial
microstructure. The real orientation distribution of the material has been
taken into account.
84.
Chen, S. P. and S. van der Zwaag (2004). "A Single-Grain Approach
Applied to the Modeling of Recrystallization Kinetics for Cold-Rolled
Single-Phase Metals." Metallurgical and Materials Transactions A
35A(3): 741-749.
A comprehensive model for the recrystallization kinetics is proposed which
incorporates both microstructural and textural components in the deformed
state. The model is based on the single-grain approach proposed previously.
The influence of the as-deformed grain orientation, which affects the stored
energy via subgrain size and sub-boundary misorientation, is taken into
account. The effects of the deformed grain geometry, the nucleation-site
density, and the initial grain size prior to deformation on the
recrystallization kinetics are assessed. The model is applied to the
recrystallization kinetics of a cold-rolled AA1050 alloy.
85.
Chen, S. P., D. N. Hanlon, et al. (2002). "Quantification of the
recrystallization behaviour in Al-alloy AA1050." Journal of Materials
Science 37: 989-995.
A new methodology for the determination of the recrystallized volume
fraction from anodically etched aluminium alloys using optical microscopy is
described. The method involves the creation of a composite image from
multiple micrographs taken at a series of orientations. The results of
quantitative analysis of images obtained by this new method are compared
with those obtained using the traditional single image optical microscopy
technique, orientation imaging microscopy (OIM) and microhardness
indentation. The multiple orientation image method is shown to consistently
yield a recrystallized volume fraction which is significantly higher than
that determined from a single image while multiple orientation imaging and
OIM results are found to be in good agreement. Furthermore it is shown that,
after the subtraction of the effect of concurrent recovery using the rule of
mixtures, microhardness indentation can also be used to determine the
recrystallized volume fraction.
86.
Chen, S., Z. Sun, et al. (2004). "Preparation and crystalline qualities
of SrTiO3 and CeO2 buffer layers fabricated on Ni substrates via a
sol–gel method for YBCO coated conductors." Physica C
412-414(Part 2): 871-876.
High purity rolled Ni substrate was annealed at 1000 °C for 60 min to
develop a cube texture with a full-width at half-maximum (FWHM) value of
5.26°. Strontium acetate, titanium (IV) butoxide, and inorganic cerium
nitrite were used as the starting materials for fabrication of
SrTiO3and CeO2 buffer layers via a sol–gel
method on the Ni substrate material. The results show that the heat
treatment temperature and holding time affect both the surface morphology
and the texture of the buffer layers. The SrTiO3 and
CeO2 buffer layers grown on the Ni substrate show a sharp (2 0 0)
orientation distribution. An intermediate layer was found between the
SrTiO3 layer and the Ni substrate. By optimizing the heat
treatment parameters, the ϖ-scan FWHM values can reach 5.31° and
6.60° for the SrTiO3 and CeO2 buffer layers,
respectively.
87.
Chen, U.-S. and H. C. Shih (2005). "Characterization of copper
metallization for interconnect by 90 degrees -bend electromagnetic filtered
vacuum arc." Nuclear Instruments & Methods in Physics Research
237(1-2): 477-483.
The cathodic arc evaporation plasma generated the highest plasma density
compared with other physical vapor deposition systems, but is known to be
contaminated with macro-particles. In order to produce high quality
particle-free copper films, a 90 ° -bend magnetic filter is suitable for
ultra-large scale integrated circuit interconnects metallization
application. Macro-particle contamination has been alleviated by
electromagnetic filter; the copper ions in the fully ionized copper plasma
were accelerated and deposited on the wafer with a negative pulsed bias
voltage. The fully ionized copper plasma stream was highly directionally
deposited on the patterned and blank wafers. Electron backscattered
diffraction spectra showed the textures distribution of the grain growth.
The result of this process as made, by mechanical pull-up tests, showed that
substrate applied with -100V pulsed bias can effectively enhance the
adhesion strength of copper film on a-TaN layer. The roughness measured by
atomic force microscope increased as the negative bias voltage applied to
the substrate increased. The filling of trench/via as narrow as 0.2
µm, with an aspect ratio as high as 5, field emission scanning
electron microscope images showed excellent gap-filling ability.
88.
Chen, W., W. Wang, et al. (2006). "Evolution of grain boundary
character distributions in Pb alloy during high temperature annealing."
Acta Metallurgica Sinica (China) 42(2): 129-133.
Grain boundary character distributions (GBCD) in Pb alloy after
thermomechanical treatments were analyzed by electron back scatter
diffraction (EBSD) and orientation imaging microscopy (OIM). The frequencies
of low Σ coincidence site lattice (CSL) grain boundaries in Pb-alloy
can be enhanced to more than 70% after proper cold rolling combined with
annealing at high temperature (0.9Tm) for a very short period of
time. Together with Σ1 boundaries, the Σ3 boundaries appeared
during recovering. The development of Σ3 boundaries in the primary
stage of recrystallization is the main reason for enhancing the frequencies
of low Σ CSL grain boundaries. Triple junctions contained three CSL
grain boundaries could be easily found in the OIM map of the specimen with
high frequencies of low Σ CSL grain boundaries, and there are specific
orientation relationships among the grains assembled by the triple
junctions.
89.
Chen, X. M., J. N. Gui, et al. (2000). "Orientation Relationships of
Martensite Variants Determined by Electron Backscatter Diffraction."
Micron 31(1): 17-25.
90.
Chen, X., J. Liu, et al. (1999). "Electron backscatter diffraction
determination of grain orientation and constituent phases." Journal of
Wuhan University 45(No. 1): 65-8.
91.
Chen, Y., K. Fujita, et al. (2003). "Development of crystalline
plasticity finite element analysis code for textural design of a dual phase
high strength and high formability steel sheet." Nippon Kikai Gakkai
Ronbunshu, A Hen (Transactions of the Japan Society of Mechanical Engineers,
Part A) 59(11): 1595-1600.
The crystal plasticity finite element (FE) method, by employing a
crystalline ODF data and "Orientation Probability Assignment
Method", has been applied for textural design of a dual phase
high-strength-and high-formability sheet steel. At first, the texture
characterization of ferrite, martensite and dual phase steels were carried
out by using EBSD and ODF analyses. Second, an optimum textural design
algorithm is proposed to find an artificial texture of dual phase steel
sheet, by combining ferrite and martensite phases, which shows high strength
and high formability, through cylindrical cup deep drawing and VDI benchmark
forming process simulations.
92.
Cheneauspath, N., R. Y. Fillit, et al. (1994). "Improved X-Ray and
Electron-Diffraction Methods for Twin Determination in Hexagonal
Crystals." Journal of Applied Crystallography 27(DEC):
980-987.
93.
Cheng, X., J. Liu, et al. (2003). Recrystallization and texture of AA 5052
alloy during annealing. Automotive Alloys 2003, Increasing Energy Efficiency
In Aluminium, And Universities Servicing Education, Research And Technology
Internationally For The Aluminium And Light Metals Industries Symposia, San
Diego, California, USA.
The recrystallization behavior and texture of continuous cast (CC) and
direct chill (DC) cast AA 5052 aluminum alloy were investigated. Evolution
of recrystallization texture in the CC and DC materials was investigated by
using three-dimensional orientation distribution functions (ODFs) that were
determined by X-ray diffraction. The electron backscatter diffraction (EBSD)
technique was adopted to study the microtexture through the thickness.
Results showed that the R and Cube orientations are the dominant
recrystallization texture components in both CC and DC materials. Stronger
Cube and R orientations are found at the surface layer than at the
half-thickness layer of cold rolled hot bands after annealing.
94.
Cheong, K.-S. and E. P. Busso (2004). "Discrete dislocation density
modelling of single phase FCC polycrystal aggregates." Acta Materialia
52(19): 5665-5675.
A new dislocation-mechanics based crystallographic theory has been developed
to model the mechanical behaviour of single-phase FCC polycrystal
aggregates. In the theory, dislocations are discretised into edge and screw
components with intrinsically different relative mobilities and are subject
to different dynamic recovery processes. The theory has been implemented
within a finite-strain and rate-dependent constitutive framework, and
applied to a thin polycrystal Cu specimen to investigate the effect of
intragranular lattice misorientations on deformation behaviour. These
misorientations are representative of low angle grain boundaries, which are
known to play an important role in the microstructural evolution of
polycrystals under monotonic and cyclic deformation. This study reveals that
the presence of these misorientations strengthen the material response by
suppressing and re-distributing the localisation of slip within the grains,
as well as inhibiting the formation of sub-grains. Through the
discretisation of dislocations, the model also predicts a higher proportion
of edge dislocations in the vicinities of localised slip regions.
95.
Cheong, S. W., E. J. Hilinski, et al. (2003). "Grain Growth in a
Low-Loss Cold-Rolled Motor-Lamination Steel." Metallurgical and
Materials Transactions A 34A(No. 6): 1321-1327.
This article attempted to determine the mechanisms governing the grain
growth process that occurs during lamination annealing of a cold-rolled
motor-lamination (CRML) steel. A new simulation approach linking a Monte
Carlo model with electron backscatter diffraction (EBSD) scans used as input
has been employed to incorporate the effects of crystollograhic texture on
the simulated grain growth process. The results from the texture analysis
and the computer simulation of the grain growth process indicate that both
stored energy driven grain growth and anistropic grain boundary growth
influence the overall grain growth occuring during lamination
annealing.
96.
Cherns, D., A. R. Preston, et al. (1988). "Electron-Diffraction Studies
of Strain in Epitaxial Bicrystals and Multilayers." Ultramicroscopy
24(4): 355-370.
97.
Cheung, C. F., W. B. Lee, et al. (2003). "Orientation changes of
aluminium single crystals in ultra-precision diamond turning." Journal
of Materials Processing Technology 140(1-3 Spec.): 346-351.
In this paper, the effects of cutting speed on the variation of surface
texture and lattice rotation of diamond-turned surfaces were investigated.
The {111} pole figures were determined at various locations by the X-ray
diffraction method. The local lattice rotation at various locations on a
machined groove by the electron back-scatter diffraction (EBSD) method was
also obtained. A simulation of the orientation change was performed and the
theoretical prediction was compared with the experimental results. Copyright
2003 Elsevier B.V. All rights reserved.
98.
Cheung, Y. L., K. C. Chana, et al. (2001). "Characterization of the
icosahedral phase in as-cast quasicrystalline
Al65Cu20Fe15 alloy." Materials
Characterization 47: 299-305.
Morphology features and microstructures of a quasicrystalline
Al65Cu20Fe15 alloy were studied using X-ray
diffraction, scanning electron microscopy (SEM), electron probe
microanalysis, electron backscattered diffraction (EBSD), and transmission
electron microscopy (TEM) techniques. A typical layer dendritic
microstructure of the as-cast quasicrystalline alloy consisted of four
phases: an Al71Cu5Fe24 phase as a core of
the dendritic structure, which was surrounded by a quasicrystalline
Al60Cu26Fe14 phase and a crystalline
Al50Cu45Fe5 phase being in the
interdendritic regions, and a Cu-rich
Al44Cu54Fe2 phase. The quasicrystalline
phase was characterized of three symmetries: five-, three-, and twofold. The
Kikuchi diffraction patterns obtained from both SEM and TEM are very
similar. It is shown that without the need to prepare thin film specimen,
EBSD is an alternative method to characterize quasicrystals.
99.
Chezan, A. R. and J. T. M. D. Hosson (2005). The role of microstructural
aspects on the performance of coarsegrained superplastic Al alloys. Textures
of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
Deformation and recrystallization texture has been investigated in Oxygen
free high conducting (OFHC) copper wires drawn at room temperature to true
strain of 2.31, and isothermally annealed at various temperatures between
150° and 750°C. Local orientations of the microstructures were
measured by means of electron backscattered diffraction (EBSD) technique.
While the drawn wire was characterized by a major<111> +
minor<100> duplex fiber texture, recrystallization occurred at
annealing temperatures between 250°C and 400°C and resulted into a
major<100>+minor<111> recrystallization texture. At temperatures
above 500°C, the <100> dominated recrystallization texture changed
to the <111> dominated growth texture due to secondary
recrystallization, which favored the <111> orientation at the expense
of the <100> component.
100.
Cho, J., C. M. Wang, et al. (2002). "A study of grain-boundary
structure in rare-earth doped aluminas using an EBSD technique."
Journal of Materials Science 37(1): 59-64.
Oversized rare-earth dopant ions such as Y3+, Nd3+,
and La3+ segregate to grain boundaries and reduce the tensile
creep rate of alpha-Al2O3 by 2-3 orders of magnitude.
It has been suspected that these dopant ions can modify the grain boundary
structure in alumina by promoting the formation of special grain boundaries.
If this were indeed the case, it would provide a possible explanation for
the aforementioned creep rate retardation. In order to test this hypothesis,
electron backscatter diffraction (EBSD) has been used to to assess both the
proportion of coincidence-site lattice boundaries, and the grain boundary
misorientation distribution, in aluminas doped with various ions (Zr, Y, Nd,
La, Nd/Zr). The results show that the grain boundary structure in alumina is
not significantly altered by the addition of the above dopants, implying
that the change in grain boundary chemistry is primarily responsible for the
observed creep behavior.
101.
Cho, J., H. M. Chan, et al. (1998). "Influence of Yttrium Doping On
Grain Misorientation in Aluminium Oxide." Journal of the American
Ceramic Society 81(11): 3001-3004.
Oversized dopant ions such as yttrium and lanthanum segregate to grain
boundaries and reduce the tensile creep rate of
alpha-Al2O3 by 2-3 orders of magnitude. One
explanation for this behaviour is that the oversized segregants give rise to
a "site-blocking" effect for grain boundary diffusion. It has also
been speculated that the dopant ions modify the grain boundary structure in
Al2O3 and reduce the creep rate by promoting the
formation of special (e.g., coincidence site lattice (CSL)) grain
boundaries. In order to test the latter hypothesis, electron backscattered
Kikuchi diffraction in the scanning electron microscope was used to
characterise the misorientation and special grain boundary distribution for
undoped and 1000-ppm-yttrium-doped Al2O3. The results
show that the grain boundary structure in Al2O3 (as
characterised by the frequency of selected CSLs and misorientation
distribution) was not significantly changed by the addition of yttrium,
indicating that creep retardation results mainly from site-blocking.
102.
Cho, J.-H. and P. R. Dawson (2006). "Investigation on Texture Evolution
during Friction Stir Welding of Stainless Steel." Metallurgical and
Materials Transactions A 37(4): 1147-1164.
103.
Cho, J.-H., A. D. Rollett, et al. (2005). "Determination of a Mean
Orientation in Electron Backscatter Diffraction Measurements."
Metallurgical and Materials Transactions A 36A(12):
3427-3438A.
The average orientation of an electron backscatter diffraction (EBSD) map is
calculated by the quaternion method and is compared with nonlinear solving
by the Hill Climbing and Barton-Dawson methods. An automated EBSD system
acquires orientations on a regular grid of pixels based on indexation of
Kikuchi patterns and the orientation is described by one of the crystal
symmetry-related equivalents. In order to calculate the quaternion average,
it is necessary to make a cloud for a set of pixels in a grain. A cloud
consists of the representative orientations with small misorientation
between each and every pair of points. The position criterion says that two
adjacent pixels have a smaller misorientation than with all others. With
this, the proper equivalent orientation, or representative orientation for
the cloud, can be selected from among all the crystal symmetry-related
equivalents. The orientation average is the quaternion summation divided by
its norm. The instant average or cumulative average is useful for dealing
with polycrystalline grains or orientation discontinuity and is also useful
for selection of the proper orientation of EBSD map with large scattering.
The quaternion, Hill Climbing, and Barton-Dawson nonlinear methods are
tested with a Gaussian distribution around the ideal texture component,
Brass {110} < 112 >. The accuracy of the three results is similar but
the nonlinear methods are associated with longer computation times than the
quaternion method. The quaternion method is adapted for characterization of
a partially-recrystallized interstitial-free (IF) steel and randomly
distributed Brass, S, and cube texture components according to several
different orientation spreads.
104.
Cho, J.-H., H.-P. Ha, et al. (2005). "Recrystallization and Grain
Growth of Cold-Rolled Gold Sheet." Metallurgical and Materials
Transactions A 36A(12): 3415-3425A.
Recrystallization and grain growth of a cold-rolled gold sheet with 98 pct
reduction in area (RA) were investigated with electron backscatter
diffraction (EBSD) and X-ray diffraction (XRD). Gold with some dopants (Be,
Ca, and La) was used in this research and its recrystallization temperature
was 320 °C. Isothermal annealing experiments at 400°C, 500°C,
and 600°C were carried out for the cold-rolled gold sheet, and
recrystallization texture was examined. In the cold-rolled gold sheet,
alpha- and beta-fibers were measured mainly and some shear texture
components were found on the surface. Shear texture components remained on
the surface for 2 hours at 400°C and were consumed by other
recrystallized grains after 24 hours at 400°C. Microstructure and
texture evolution during in-situ annealing at 400°C were investigated
from the cold-rolled state to the fully recrystallized state using EBSD Most
of the newly, recrystallized grains came from the deformed beta-fiber
regions and consisted of beta-fiber, cube, and other random
orientations.
105.
Cho, J.-H., J. S. Cho, et al. (2002). Characterization of Cold Drawn Gold
Bondong Wire with EBSD. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
Cold drawn gold bonding wires have been investigated with Electron Back
Scatter Diffraction (EBSD). The textures of drawn gold wires contain major
<111>, minor <100>, and small fractions of complex fiber
components. The <100> oriented regions are located in the center and
surface of the wire, and the complex fiber component regions are located
near the surface. The <111> oriented regions occur throughout the wire
and have large Taylor factors and would be expected to have higher stored
energy as a result of plastic deformation compared to the <100>
regions. Large misorientations (angles > 40°) are located between the
<111> and <100> regions, which means that the boundaries between
them are likely to have high mobility. Boundaries within the <111>
regions are predominantly <111> tilt grain boundaries with large
misorientations; similarly the <100> regions have <100> tilt
grain boundaries with smaller misorientations. It appears that the stored
energy as indicated by geometrically necessary dislocation content in the
subgrain structure is similar in all orientatios desoite the large
differences in Taylor factor.
106.
Cho, J.-H., J.-S. Cho, et al. (2003). "Recrystallization and Grain
Growth of Cold-Drawn Gold Bonding Wire." Metallurgical and Materials
Transactions A 34A(5): 1113-1125.
Recrystallization and grain growth of gold bonding wire have been
investigated with electron backscatter diffraction (EBSD), The bonding wires
were wire-drawn to an equivalent strain greater than 11.4 with final
diameter between 25 and 30 µm. Annealing treatments were carried out
in a salt bath at 300° C, and 400° C for 1, 10, 60 minutes and 1
day. The textures of the drawn gold wires contain major <111>, minor
<100>, and small fractions of complex fiber components. The
<100> oriented regions are located in the center and surface of the
wire, and the complex fiber components are located near the surface. The
<111> oriented regions occur throughout the wire. Maps of the local
Taylor factor can be used to distinguish the <111> and <100>
regions. The <111> oriented grains have large Taylor factors and might
be expected to have higher stored energy as a result of plastic deformation
compared to the <100> regions. Both <111> and <100> grains
grow during annealing. In particular, <100> grains in the surface and
the center part grow into the <111> regions at 300° C and 400°
C. Large misorientations (angles > 40 deg) are present between the
<111> and <100> regions, which means that the boundaries between
them are likely to have high mobility. Grain average misorientation (GAM) is
greater in the <111> than in the <100> regions. It appears that
the stored energy, as indicated by geometrically necessary dislocation
content in the subgrain structure, is larger in the <111> than in the
<100> regions.
107.
Cho, J.-H., S.-J. Park, et al. (2002). Deformation Texture of Cold Drawn
Al6063 Tube. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Texture evolution durig cold drawing of 6063 (Al-0.7%Mg-0.4%Si) tube is
investigated. The experimental texture is measured with X-ray and EBSD
together. The initial tube is made by hot extrusion, and it has texture
gradient through thickness direction. The inner and outer surfaces of
initial tube have similar textures, but the center part has different
textures. These texture gradients are decreasing during cold drawing. The
overall texture of tube through thickness is measured with the stacking
specimens of several tube pieces in X-ray. This result shows that overall
texture of tube is similar to that of center part of tube. Characterization
of EBSD data shows that the grain size is decreasing and the low angle grain
boundaries are increasing during drawing. These come from the subdivision of
grains during deformation. Lattice rotation field shows that drawing
deformation in tube is related to rolling, and rotated cube {100}<011>
is convergent and stable. With FEM analysis, the friction and reduction
effects on textures are investigated. FEM analysis and crystal plasticity
model predict texture evolutions reasonably.
108.
Cho, J.-Y. and J. A. Szpunar (2002). The Effect of Grain Boundary Character
Distribution (GBCD) on Edge Cracking during Hot Rolling of Austenitic
Stainless Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
A possible influence of grain boundary character distribution (GBCD) on edge
crack propagation during planetery hot rolling of austenitic stainless steel
is investigated. GBCD of two specimens which were selected from the edge and
the middle parts of hot-rolled plate was calculated from ODF (orientation
distribution function). To analyze a relationship between the structure of
grain boundary network and crack propagation in the samples investigated,
microcrack characteristics were analyzed in details by orientaiton imaging
microscopy (OIM). In this investigation, it was found that the inhomogeneity
of GBCD in through thickness layers is an important factor for understanding
crack propagation. The cracks propagate through the areas where there is a
concentration of high energy boundaries.
109.
Cho, J.-Y. and J. A. Szpunar (2002). The Effect of Substrate Texture and
Electroplating Conditions on the Texture and Surface Morphology of Copper
Electrodeposits. ICOTOM 13, Seoul, Korea, Trans Tech Publications
Inc.
Cu electroplating is a key process in manufacturing interconnects in
electronic chips. Electroplating techniques have been studied extensively in
the past, however, the influence of substrate texture and electroplating
conditions on the texture and surface morphology of the electrodeposits is
still unclear. In this study, a role of various electroplating conditions
and substrates having different textures are investigated. Three different
polycrystalline copper specimens are used as substrates and electrodeposits
are plated using different current densities. the surface morphology of the
deposits was analyzed by SEM and AFM, and the microstructure and texture
were measured by X-ray and OIM (EBSP). The mechanism of growth of Cu
deposits and the importance of smooth surface morphology are
analyzed.
110.
Cho, J.-Y., H. Kim, et al. (2004). Textural evolution of Cu damascene
interconnects after annealing. Materials, Technology and Reliability for
Advanced Interconnects and Low-k Dielectrics - 2004, San Francisco,
California, USA.
Textural evolution of Cu interconnects having a different line width was
investigated after annealing. Texture was measured on the surface of Cu
interconnects using EBSD (electron backscattcred diffraction) techniques
including GBCD (grain boundary character distribution). To analyze a
relationship between the stress distribution and textural evolution in the
samples investigated, the micro stresses were calculated for the different
line width at 200n with pe C using FEM (finite element modeling). In this
investigation, it was found that the inhomogeneity of stress distribution in
Cu interconnects is an important factor is necessary for understanding
textural transformation after annealing. A new interpretation of textural
evolution in damascene interconnects lines after annealing is suggested,
based on the state of stress and the growth mechanisms of Cu
electrodeposits.
111.
Cho, J.-Y., H.-J. Lee, et al. (2004). Textural and microstructural
transformation of Cu damascene interconnects after annealing. Symposium on
Challenges in Advanced Thin Films: Microstructures, Interfaces and
Reactions, Charlotte, North Carolina, USA, TMS; IEEE.
Influence of annealing on the textural and microstructural transformation of
Cu interconnects having various line widths is investigated. Two types of
annealing steps have been considered here: room temperature over 6 months
and 200°C for 10 min. The texture was determined by X-ray diffraction
(XRD) of various cross-sectional profiles after electropolishing, and the
surface, microstructure, and grain boundary character distribution (GBCD) of
Cu interconnects were characterized using electron backscattered diffraction
(EBSD) techniques. In order to analyze a relationship between the stress
distribution and textural evolution in the samples, microstresses were
calculated with decreasing line widths at 200°C using finite element
modeling (FEM). In this investigation, it was found that the inhomogeneity
of stress distribution in Cu interconnects is an important factor, which is
necessary for understanding textural transformation after annealing. A new
interpretation of textural evolution in damascene interconnects lines after
annealing is suggested, based on the state of stress and the growth
mechanisms of Cu electrodeposits.
112.
Cho, J.-Y., H.-J. Lee, et al. (2005). "The Effect of Stress
Distribution onTexture Evolution of Cu Damascene Interconnects During
Annealing." Archives of Metallurgy and Materials 50(1):
261-266.
Textural changes of Cu interconnect having different line width was
investigated after annealing. Texture was measured using XRD (x-ray
diffraction) and the surface texture was investigated using EBSD (electron
backscattered diffraction) techniques. To analyze a relationship between the
stress distribution and textural evolution observed in the samples, the
stresses were calculated for the different line width at 200DGC using FEM
(finite element modeling) along the width and depth of the line. In this
investigation, it was found that the inhomogeneity of stress distribution in
Cu interconnects is an important factor necessary for understanding textural
transformation during annealing. Textural evolution in damascene
interconnects lines after annealing is discussed, based on the state of
stress in Cu electrodeposits.
113.
Cho, J.-Y., H.-J. Lee, et al. (2005). Texture Investigation in Cu Damascene
Interconnects during Annealing. Textures of Materials - ICOTOM 14, Leuven,
Belgium, Trans Tech Publications.
Textural changes of Cu interconnects having a different line width were
investigated after annealing. Texture was measured by XRD (x-ray
diffraction) at different depth of the interconnect line and on the surface
of interconnects using EBSD (electron backscattered diffraction) techniques.
To analyze the relationship between the stress distribution and textural
evolution observed in the different samples, the stresses were calculated
for the different line width at 200°C using FEM (finite element
modeling) along the width and depth of the line. In this investigation, it
was found that the inhomogeneity of stress distribution in Cu interconnects
is an important factor necessary for understanding textural transformation
during annealing. Textural evolution in damascene interconnects lines during
annealing is discussed, based on the state of stress in Cu
electrodeposits.
114.
Cho, J.-Y., K. Mirpuri, et al. (2005). "Texture investigation of copper
interconnects with a different line width." Journal of Electronic
Materials 34(1): 53-61.
To understand the effect of line width on textural and microstructural
evolution of Cu damascene interconnect, three Cu interconnects samples with
different line widths are investigated. According to X-ray diffraction (XRD)
results, the (111) texture is developed in all investigated lines. Scattered
{111}<112>and {111}<110> texture components are present in 0.18-
mu m-width interconnect lines, and the {111}<110> texture was
developed in 2- mu m-width interconnect lines. The directional changes of
the (111) plane orientation with increased line width were investigated by
XRD. In addition, microstructure and grain-boundary character distribution
(GBCD) of Cu interconnect were measured using electron backscattered
diffraction (EBSD) techniques. This measurement demonstrated that a
bamboo-like microstructure is developed in the narrow line, and a
polygranular structure is developed in the wider line. The fraction of Sigma
3 boundaries is increased as the line width increases but is decreased in
the blanket film. A new interpretation of textural evolution in damascene
interconnect lines after annealing is suggested, based on the state of
stress and growth mechanisms of Cu deposits.
115.
Cho, J.-Y., T. Inoue, et al. (2004). "Effect of shear deformation on
microstructural evolution of Ni-30Fe alloy during hot deformation."
Materials Transactions 45(10): 2966-2973.
Electron backscattered diffraction analysis has been used to investigate the
effect of shear deformation on the microstructural evolution of a Ni-30Fe
alloy during hot deformation. The alloy was compressed by 50% or 75% in
thickness at a strain rate of 1/s in a single pass at 1023 K using a hot
compression simulator. An explicit finite element analysis was carried out
to evaluate the inhomogeneous strain distribution introduced in the
specimens by hot compression simulator. As the equivalent strain increased,
the fraction of high angle grain boundaries with misorientations between 15
degrees and 30 degrees increased almost in the similar way regardless of the
presence of shear strain. The fraction of high angle grain boundaries having
misorientations in excess of 30 degrees increased mainly at the expense of
low angle grain boundaries with misorientations smaller than 15 degrees.
Such the expense occurred at much higher rate with shear strain than without
shear strain. The compressive direction changed continuously in the areas
with shear strain component during deformation, which was thought to
accelerate the subdivision of austenite grain interiors with increased
misorientations between subdivided local areas.
116.
Cho, Y. K. and D. Y. Yoon (2004). "Faceting of High-Angle Grain
Boundaries in Titanium-Excess BaTiO3." Journal of the
American Ceramic Society 87(3): 438-442.
The grain boundaries in BaTiO3 with excess Ti of 0.5, 0.3, and
0.1 at.% sintered at 1300° or 1250 containing C have been examined by
scanning electron microscopy (SEM), electron backscattered diffraction
pattern (EBSP), and transmission electron microscopy (TEM). In the 0.1%
Ti-excess specimen, large grains growing abnormally form high-angle grain
boundaries when they impinge on each other as verified by EBSP. A large
fraction of these grain boundaries are faceted with hill-and-valley shapes.
In the 0.5% Ti-excess specimen, large grains growing abnormally are
elongated in the directions of their {111} double twins. These grains often
form flat grain boundaries parallel to their {111} planes with the fine
matrix grains, and the grain-boundary segments between the large impinging
grains with high misorientation angles are often also parallel to the {111}
planes of one of the grains. These grain boundaries are expected to be
singular. Most of the grain boundaries between the randomly oriented
fine-matrix grains in the 0.3 at.% Ti-excess specimen are also faceted with
hill-and-valley shapes at finer scales when observed under TEM. The facet
planes are parallel to {111}, {011}, and {012} planes of one of the grain
pairs and are also expected to be singular. These high-angle grain
boundaries lying on low index planes of one of the grain pairs are similar
to those observed in other oxides and metals.
117.
Cho, Y. W., H.-H. Jin, et al. (2003). "Formation of intragranular
acicular ferrite grains in a Ti-containing low carbon steel." ISIJ
International 43(7): 1111-1113.
The role of non-metallic inclusions and the nucleation mechanism of
intragranular ferrite grains was investigated by electron microscopy (TEM,
EBSD) in Ti-containing low carbon steel. Intragranular ferrite grains are
formed from complex inclusions (Ti2O3 + TiN, TiN +
MnS). However, the TiN particles are an inclusion that most effectively
promotes intragranular ferrite nucleation in this steel. One or more ferrite
grains were nucleated from a TiN particle but all ferrite trains have a B-N
orientation relationship with the TiN particle. The observed B-N
relationship between the intragranular ferrite grains and the TiN particle
suggests that the intragranular nucleation of ferrite from these complex
inclusions is promoted by the crystal cohereny of TiN with ferrite. (Edited
abstract)
118.
Choi, J.-J., G.-T. Park, et al. (2004). "Effects of lanthanum nitrate
buffer layer on the orientation and piezoelectric property of
Pb(Zr,Ti)O3 thick film." Journal of Materials Research
19(12): 3671-3678.
Highly oriented Pb(Zr,Ti)O3 (PZT) films were deposited on
Pt/Ti/SiO2/Si substrates by the sol-gel method using lanthanum
nitrate as a buffer layer. When the lanthanum nitrate buffer layer was heat
treated at temperatures between 450 and 550 °C, the PZT layer coated
onto this buffer layer showed a strong (100) preferred orientation.
Regardless of the other deposition conditions, such as the pyrolysis
temperature, pyrolysis time, annealing temperature and heating rate, the
film deposited on the buffer layer had this orientation. Thick films were
also fabricated using the sol-gel multi-coating method, and the (100)
texture was found to be maintained up to a thickness of 10 µm. The
ferroelectric hysteresis and piezoelectric coefficient (d33) of
highly oriented PZT thick films were characterized, and the (100) oriented
PZT film showed higher piezoelectric property than the (111) oriented
film.
119.
Choi, J.-J., G.-T. Park, et al. (2005). "Ferroelectric and
piezoelectric properties of highly oriented Pb(Zr,Ti)O3 film
grown on Pt/Ti/SiO2/Si substrate using conductive lanthanum
nickel nitrate buffer layer." Journal of Materials Research
20(3): 726-733.
The orientation and electrical properties of Pb(Zr,Ti)O3 thin
films deposited on a Pt/Ti/SiO2/Si substrate using lanthanum
nickel nitrate as a conductive buffer layer were analyzed. The lanthanum
nickel nitrate buffer layer was not only electrically conductive but also
effective in controlling the texture of the PZT thin film. The role of the
lanthanum nickel nitrate buffer layer and its effects on the orientation of
the PZT thin film were analyzed by x-ray diffraction, electron beam
back-scattered diffraction, and scanning electron microscopy. The annealed
lanthanum nickel nitrate buffer layer was sufficiently conducting for use in
longitudinal electrode configuration devices. The dielectric, ferroelectric,
and piezoelectric properties of the highly (100) oriented PZT films grown
with the lanthanum nickel nitrate buffer layer were measured and compared
with those of (111) and (100) oriented PZT films deposited without a buffer
layer.
120.
Choi, S.-H. (2002). Monte Carlo Technique for Simulation of
Recrystallization Texture in Interstitial Free Steels. ICOTOM 13, Seoul,
Korea, Trans Tech Publications Inc.
A Monte Carlo technique was used to simulate primary recrystallization in IF
steels. In order to consider anisotropic properties of grain boundary energy
and grain boundary mobility, functions of boundary misorientation and
coincident site lattice (CSL) were introduced. In order to consider the
energy stored within a grain, a parameter Q describing the pattern quality
in Electron Backscatter Diffraction measurement was used. The EBSD
measurement result of local area was analyzed to examine the possibilty of
the model to simulate the evolution of microstructure and texture during
recrystallization. The nucleation sites of recrystallization were high angle
grain boundaries (HAGBs) and shear bands. The main texture components of
simulation were quite similar with those obtained experimentally
121.
Choi, S.-H. and J. H. Cho (2005). "Primary recrystallization modelling
for interstitial free steels." Materials Science and Engineering A
405(1-2): 86-101.
A two-dimensional (2D) Monte Carlo (MC) technique was used to simulate
primary recrystallization in interstitial free (IF) steel. In order to
consider anisotropic properties of grain boundary energy and grain boundary
mobility, functions of boundary misorientation were introduced.
Orientation-dependent stored energy developed in 80% cold-rolled IF steel
was evaluated by reconstructing of data measured using electron
back-scattered diffraction (EBSD) analysis. Subgrain method based on
subgrain structure is used for quantitative analysis of the stored energy.
The simulation shows that the recrystallized volume fraction at the initial
stage of recrystallization affects recrystallization texture. An
inhomogeneous distribution of stored energy and a severe spread of
orientations induce inhomogeneous nucleation and large scattering of
orientation in recrystallized grains. The nucleation sites of IF steels at
an initial stage of recrystallization were high angle grain boundaries
(HAGBs) and grain interiors. The main texture components obtained by the
simulation were quite similar with those obtained experimentally.
122.
Choi, S.-H. and K.-G. Chin (2004). Evaluation of Stored Energy in
Cold-Rolled IF Steels from EBSD Data and Its Application to
Recrystallization Modeling. Second Joint International Conference on
Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France,
Trans Tech Publications Ltd.
This study has been conducted to evaluate the orientation-dependent stored
energy of deformed grains from the data measured using electron backscatter
diffraction (EBSD) analysis. The sored energy in deformed grains is an
important term as a driving force for static recrystallization of
cold-rolled steels. Subgrain method based on subgrain structure is used for
quantitative analysis of the stored energy developed in cold-rolled
interstitial free (IF) steels to a reduction of 80%. The
orientation-dependent stored energy term was used in Monte Carlo technique
to simulate static recrystallization of IF steels.
123.
Choi, S.-H. and Y.-S. Jin (2004). "Evaluation of stored energy in
cold-rolled steels from EBSD data." Materials Science and Engineering A
371(1-2): 149-159.
This study has been conducted to evaluate the orientation-dependent stored
energy of deformed grains from the data measured using electron
back-scattered diffraction (EBSD) analysis. The stored energy in deformed
grains is an important term as a driving force for static recrystallization
of cold-rolled steels. Subgrain method based on subgrain structure is used
for quantitative analysis of the stored energy developed in cold-rolled low
carbon steels to a reduction of 50% and compared with conventional methods.
The result demonstrated that the main texture components having high stored
energy are mainly of {554} (225) orientation and partially gamma -fibre
orientations. The subgrain method appears to be a proper method to evaluate
the spatial distribution of stored energy as a function of
orientation.
124.
Choi, W. S., H. S. Ryoo, et al. (2002). "Microstructure Evolution in Zr
under Equal Channel Angular Pressing." Metallurgical and Materials
Transactions A 33(March): 973-980.
Pure Polycrystalline Zr was deformed by equal channel angular pressing
(ECAP), and the microstructural characteristics were analyzed. By repeated
alternating ECAP, it was possible to refine the grain size from 200 to
0.2µm. Subsequent annealin heat treatment at 550 °C resulted in a
grain growth of up to 6µm. Mechanical twinning was an important
deformation mechanism, particularly during the early stage of deformation.
The mosat active twinning system was identified as 85.2 deg
{1012}<1011> tensile twinning, followed by 57.1 deg
{1011}<1012>compressive twinning. Crystal texture as well as
grain-boundary misorientation distribution of defirned Zr were analyzed by
X-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The
ECAP-deformed Zr showed a considerable difference in the crystallographic
attributes from those of cold-rolled Zr or Ti, in that texture and boundary
misorientation-angle distribution tend toward more even distribution with a
slightly preferemtial distribution of boundaries of a 20 to 30 deg
misorientation angle. Furthermore, unlike the case of cold-rolling,
thecrystaltexture was not greatly altered by subsequent annealing heat
treatment. Overall, the present work suggests ECAP as a viable method to
obtain significant grain refining in hexagonal close-packed (hcp)
metals.
125.
Choi, Y. S., H. R. Piehler, et al. (2004). "Formation of Mesoscale
Roughening in 6022-T4 Al Sheets Deformed in Plane-Strain Tension."
Metallurgical and Materials Transactions A 35A(2): 513-524.
Mesoscale surface-roughening evolution in 6022-T4 Al sheets was investigated
using plane-strain tension. The formation of grain-scale hills and valleys
and their relation to the morphologies and corresponding orientations of
surface grains after deformation were examined experimentally. These
observations were analyzed using various approaches based on the Schmid and
Taylor crystal plasticity models. It was observed that surface grains with
and without slip bands tend to form valleys and hills, respectively,
wherever these two types of grains are adjacent to each other along the
planestrain tension direction. When the sample was pulled along the
transverse direction, the formation of hills and valleys by unbanded and
banded grains was more lineally organized in the plane-strain (rolling)
direction than in the sample that was pulled along the rolling direction
(RD). Slip banding and valley formation were principally observed in the
surface grains with either very few (1 to 2) slip systems of high Schmid
factors or with low Taylor factors, in contrast to nonslip-banded and
hill-forming surface grains. Quantitative analysis using correlation
coefficients showed that the Schmid factor provided slightly better
agreement than the Taylor factor in predicting the slip-banding (and
valley-forming) and nonslip-banding (and hill-forming) behaviors of surface
grains. In addition, measures that quantify the image qualities of electron
backscattered diffraction (EBSD) patterns for selected surface grains
suggested that the slip-banded and valley-forming grains contain less
lattice distortion than the nonslip-banded and hill-forming grains, despite
the larger strains experienced by these grains. This indicates that
dislocations in the slip-banded grains move out of the surface to create
deformation without lattice distortion. Plastic interactions between
specific neighboring grains are central to the formation of mesoscale
surface roughening.
126.
Chou, A. C. and H. C. Eaton (1983). "Dislocation-Structures in the Near
Sigma-3 Twin Boundaries in Nickel." Scripta Metallurgica 17(11):
1319-1324.
127.
Chou, C. T. (2004). Random probability calculations in texture measurements.
Microscopy and Microanalysis 2004, Savannah, Georgia, USA, Cambridge
University Press.
In a texture measurement a “tolerance angle” is needed to define
the crystal orientations that are included in a texture. This tolerance
angle may be selected as a misorientation angle, as a Gaussian half scatter
width in the series expansion or the Gaussian kernel estimation in the ODF
calculations.
128.
Chou, C. T., K. G. Dicks, et al. (2002). Interactive and Quantitative
Texture Determination by Consecutive Inverse Pole Figures. ICOTOM 13, Seoul,
Korea, Trans Tech Publications Inc.
A new method, the 'consecutive inverse pole figure method' for texture
determination has been developed. In this method the data set of individual
crystal orientations, obtained by Electron Backscatter Diffraction (EBSD)
Crystal Orientation Mapping (COM) of a sample, are divided into subgroups,
according to their positions in the ND and RD inverse pole figure
sequentially (conversely using RD and ND in sequence), to find a texture
component. By repeating the procedure, different texture components in the
sample are determined.
129.
Chou, C. T., P. Rolland, et al. (2002). A New Method for Analyzing Electron
Backscatter Diffraction (EBSD) Data for Texture using Inverse Pole Figures.
Microscopy and Microanalysis 2002, Québec City, Québec,
Canada, Cambridge University Press.
130.
Chou, C. T., P. Rolland, et al. (2002). The Random Orientation Probability
in Consecutive Inverse Pole Figure Method for Texture Determination.
Microscopy and Microanalysis 2002, Québec City, Québec,
Canada, Cambridge University Press.
131.
Chou, J.-T., H. Shimauchi, et al. (2005). "Preparation of samples using
a chemical etching for SEM/EBSP method in a pure magnesium polycrystal and
analysis of its twin boundaries." Journal of Japan Institute of Light
Metals 55(3): 131-136.
In order to establish a preparation method of pure magnesium samples for OM
and SEM/EBSP method, the surfaces of magnesium polycrystal were chemically
polished by various solutions. For OM observation and twin observation for
SEM/EBSP method, the optimum etching condition was chemical polishing with
20% hydrochloric acid ethanol and 5% nitric acid ethanol. For SEM/EBSP
analysis, the optimum etching condition was chemical polishing with a
mixture of, nitric acid, hydrochloric acid and dehydrated ethanol of 1:2:7
in volume ratio. Furthermore, in this study, the crystal orientations of
pure magnesium polycrystal treated with above solution were analyzed by
SEM/EBSP method. It was found that there are many twins in the samples and
all the twins are (1012) type twin. In addition, it was clarified that the
orientation relationships between a twin and a neighbor grain and between
twins have specific features. When the tip of twin was on boundary, the
misorientation of twin and neighbor grain was about 40 degree. When a twin
pierced through a grain boundary, the misorientation between twin and
neighbor grain was about 75 degree. When twins were crossed each other and
the tip of twin touched the other twin, the misorientation of twins was
about 60 degree.
132.
Choudhary, B. K., E. I. Samuel, et al. (2001). "Tensile-Stress-Strain
and Work-Hardening Behavior of 316Ln Austenitic Stainless-Steel."
Materials Science and Technology 17(2): 223-231.
133.
Choy, K.-L., M. Wei, et al. (2006). "Electrostatic spray assisted
vapour deposition and structural characterisation of cerium oxide films on
biaxially textured Ni tapes." Materials Letters 60(12):
1519-1523.
CeO2 thin films were successfully deposited onto biaxially
textured Ni tapes at a temperature between 400 and 600ured Ni t C using
electrostatic spray assisted vapour deposition (ESAVD). The surface
morphology and microstructure of the deposited CeO2 films were
characterized using high-resolution scanning electron microscopy. The
preferred orientation of both Ni tape and CeO2 films was
characterised using both X-ray diffraction and pole figure measurements. It
has been found that highly textured CeO2 films were formed
epitaxially on biaxially textured Ni substrates. The orientation
relationships between CeO2 film and Ni substrate are
001CeO2 //001 Ni and 110CeO2 //100
Ni. FWHM of the 111 φ scans from both film and substrate were
also recorded and compared, which shows the good CeO2 film
alignment has been achieved. The results show that ESAVD is a promising and
cost-effective deposition technique to form thin epitaxial CeO2
buffer layers onto Ni tapes for subsequent deposition of high-temperature
superconducting oxides.
134.
Christ, H.-J., O. Duber, et al. (2006). "Characterizing the
microstructure of multiphase materials using EBSD." Practical
Metallography 43(2): 88-102.
The Electron Back Scatter Diffraction (EBSD) technique was employed to
prepare microstructural images of an austenitic-ferritic duplex steel and
discriminate between grain boundaries and phase boundaries. The condition of
the material was subjected to a heat treatment by annealing the material for
4 hours, cooling it down slowly,and quenching it into the water. The
stereological parameters were used to determine the obstructing effect of
various boundary types on the propagation of cracks. The orientation data
were used to determine the the spatial position of slip planes, which allows
to draw conclusions regarding the mechanisms accountable for the propagation
of cracks. (Edited abstract)
135.
Chu, J. P., H. Y. Yasuda, et al. (2000). "Electron Backscattered
Diffraction Study on Superplastic Coarse-Grained Fe-27 at Percent-Al -
Processing Effects." Intermetallics 8 (9-11): 1075-1079.
136.
Chu, J. P., H. Y. Yasuda, et al. (2000). Superplasticity of Coarse-Grained
Fe-27at.0AAl: Optical Microstructure andElectron Backscattered Diffraction
Studies. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
Microstructure of coarse-grained Fe-27at.%Al alloy has been examined after
superplastic deformation. The alloy with an initial grain size of ~1.6 mm is
tensile tested under initial strain rates of 1x10-4 and
1x10-2 sec-1at 800 and 900° C.
Elongation-to-failure obtained are at least 183%, with the maximum of 420%
at 800° C, 1x 10-4 sec-1, confirming the
superplastic property. At 800° C, the high strain-rate deformation
results in a grain-migration structure and a poor elongation is thus
obtained. Nevertheless, at 900° C, a better elongation is obtained under
the high strain-rate deformation. To achieve a greater elongation and
refined grain structures after deformation, the superplastic deformation
needs to carry out at 800° C with a strain rate of 1x 10-4
sec-1 or at 900° C with 1x10-2 sec-1.
Electron backscattered diffraction results show that numerous subgrains are
present after deformation at 800° C with 1x10-2
sec-1, Yet, these subgrains are relatively smaller in size, but
much dense in population. Therefore, the grain bulging becomes larger in
extent at lower strain rates, resulting in the dynamic recrystallization. At
higher strain rates, the grain boundaries are frequently serrated, an
evidence of grain-boundary migration.
137.
Chu, J. P., J. H. Wu, et al. (2000). "Electron Backscattered
Diffraction Study on Superplastic Properties of Coarse-Grained Fe-27 at
Percent-Al." Intermetallics 8(1): 39-46.
An electron backscattered diffraction technique has been used to investigate
crystallographic features of a superplastic coarse-grained Fe-27 at % Al
alloy. Alloy samples studied have been tensile tested in a temperature range
between 600 and 800°C in air under an initial strain rate of 1 x
10-4s-1. As a result of dynamic recovery and
recrystallization, the grain structure undergoes four major transitions:
subgrain-boundary formation, grain-boundary migration, formation and growth
of recrystallized grains. A model based on the microstructural evolution is
described. Subgrains form during an initial stage of high-temperature
deformation when deformation is conducted at low temperature
(600°C).Upon further deformation at 700°C, grain boundaries migrate,
resulting in the formation of new grains. When deformation is made further
to a larger elongation or at even higher temperature (800°C), dynamic
recovery and recrystallization occur significantly, resulting in grain
refinement and hence superplasticity. Refined grains thus formed maintain
crystallographic relationships with parent grains.
138.
Chu, L. H., R. L. Hwang, et al. (2004). Novel EBSD sample preparation and
applications to failure analysis cases. 11th International Symposium on the
Physical and Failure Analysis of Integrated Circuits, IPFA 2004, Taiwan,
IEEE.
Electron beam backscatter diffraction (EBSD) can provide valuable local
microstructural information for crystalline materials such as grain size,
grain orientation, and texture. However when this method is applied to
Cu/low-k dielectrics, factors such as charging, drifting and instability of
the low-k material can seriously compromise the quality of the EBSD data.
Sample preparation techniques, for both top view and cross-sectional
samples, are introduced in this work to minimize these effects and enable
acquisition of EBSD data with good quality. Some of the factors that affect
the quality of EBSD data can be correlated to physical or electrical data,
in particular one example shows that degradation in the quality of the EBSD
data in a Cu via can explain the higher resistance measured in that via
Copyright 2004 IEEE.
139.
Chu, R. Q., Z. Cai, et al. (2001). "Fatigue crack initiation and
propagation in an α -iron polycrystal." Materials Science and
Engineering 313: 64-68.
The cyclic deformation and crack initiation and propagation of α-iron
polycrystals have been studied under stress-control with emphasis on the
dependence on the stress amplitudes and orientation of grains. The
orientations of grains surrounding cracks were determined by the electron
backscatter diffraction (EBSD). It was found that cracks did not originate
at grain boundaries but along the slip lines intersecting with the free
surface at the corner of the specimen. At lower stress amplitude, the crack
propagated in a transgranular mode, but at higher stress amplitude the crack
propagated in a mixed mode–transgranular mode and intergranular mode.
The stress distribution along the loading axis of grains surrounding the
crack was calculated using a three-dimensional anisotropic finite element
method (FEM). In the present work, it was shown that the crack initiation
mainly depends on three factors: higher stress distribution, abundant
dislocation sources and less resistance to dislocation motion.
140.
Chun, Y. B., S. K. Hwang, et al. (2004). "Evolution of deformation and
recrystallization textures in coldrolled CP-Ti - Experiments and MC
simulation." JOM 56(11): 156.
The development of deformation texture in CP-Ti during cold rolling (10%
similar to 90%) and the evolution of the recrystallization texture during
subsequent heat treatment were determined experimentally using XRD and EBSD
and modeled using Monte-Carlo computer simulations. For a low- to-medium
level of deformation (up to 40%), twinning governed the deformation and gave
rise to a normal basal texture. For higher levels of deformation (up to
90%), however, the main deformation mechanism was slip, and a bi-modal basal
texture with peaks at j1=0', F=35', j2=30' was developed. Recrystallization
annealing suppressed the cold-rolling texture and introduced instead two new
texture components (j1=15', F=35', j2=35' and j1=0', F=35', j2=0'), whose
intensities significantly increased during the grain-coarsening stage of
recrystallization and grain growth. From the EBSD analysis, it was found
that grains with the major recrystallization-texture components had
considerably larger grain sizes than others. A two-dimensional Monte-Carlo
simulation was conducted to trace the evolution process of the major
recrystallization-texture components. The fact that the intensification of
the recrystallization texture occurred during the grain-coarsening stage,
found by EBSD-mapping method, was also confirmed by the simulation. The
present results suggest that the heterogeneous grain-size distribution
during the recrystallization process was responsible for the evolution
characteristics of the recrystallization texture in CP-Ti.
141.
Chun, Y. B., S. L. Semiatin, et al. (2005). Role of Deformation Twinning in
Cold Rolling and Recrystallization of Titanium. Textures of Materials -
ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The evolution of microstructure and texture during cold rolling and
recrystallization annealing of commercial-purity Ti (CP- Ti) was
established. Cold rolling to 40% reduction activated mechanical twinning-
mostly {1122}<1123>compressive twins and {1012}<1011>tensile
twins. The formation of twins resulted in an inhomogeneous microstructure,
in which only the localized regions containing twins were refined and the
regions deformed by slip remained coarse. The twinned grains, containing
high stored energy and numerous high-angle grain boundaries, became the
preferential sites of nucleation during subsequent recrystallization. During
recrystallization heat treatment at 500~700°C, the cold-rolling texture
(φ1=0°, Φ=35°,φ2=30°)
diminished in intensity, whereas a recrystallization texture component
(φ1=15°, Φ=35°,φ2=35°)
appeared. The recrystallization heat treatment temperature affected the rate
of recrystallization but not the texture characteristics per se. During the
subsequent grain growth stage, the recrystallization texture component
increased. This behavior was attributed to the growth of larger-than-average
grains of this particular crystal orientation.
142.
Chung, Y. H., M. Y. Huh, et al. (2003). Formation of shear texture and
ultra-fine grains during equal angular channel rolling and subsequent
annealing in AA 3003 sheet. Designing, Processing and Properties of Advanced
Engineering Materials: Proceedings on the 3rd International Symposium on
Designing, Processing and Properties of Advanced Engineering Materials, Jeju
Island, South Korea.
The evolution of texture and microstructure during the equal channel angular
rolling (ECAR) and subsequent annealing in aluminum alloy 3003 sheets was
investigated. The tools of ECAR were designed to provide a constant shear
deformation of the order of 0.5 per passage while preserving the original
sheet shape. Samples of the aluminum alloy 3003 sheets were repeatedly
deformed by ECAR up to twelve passages. Shear textures developed after the
first passage of ECAR. However, the intensity of shear texture components
decreased with increasing number of ECAR passages. After a large number of
ECAR passages, a random texture developed at the expense of shear texture
components. Observations by TEM and EBSD revealed that the degree of
misorientations within the deformed grains increased with increasing number
of ECAR passages. After recrystallization annealing, samples deformed by
ECAR displayed pronounced {111}//ND fiber orientations. The annealed sheets
comprising of ultra-fine grains were successfully produced in the samples
deformed by a large number of ECAR passages.
143.
Cizek, P., B. P. Wynne, et al. (1996). "Deformation banding in (001)
[110] textured aluminum sheet deformed in tension." Materials Science
and Engineering 219: 44-55.
144.
Cizek, P., F. Bai, et al. (2004). "Fine Structure of Shear Bands Formed
during Hot Deformation of Two Austenitic Steels." Materials
Transactions 45(7).
Shear bands formed during both cold and hot plastic deformation have been
linked with several proposed mechanisms for the formation of ultrafine
grains. The aim of the present work was to undertake a detailed
investigation of the microstructural and crystallographic characteristics of
the shear bands formed during hot deformation of a 22Cr-19Ni-3Mo (mass%)
austenitic stainless steel and a Fe-30 mass%Ni based austenitic model alloy.
These alloys were subjected to deformation in torsion and plane strain
compression (PSC), respectively, at temperatures of 900DGC and 950DGC and
strain rates of 0.7s-1 and 10s-1, respectively.
Transmission electron microscopy and electron backscatter diffraction in
conjunction with scanning electron microscopy were employed in the
investigation. It has been observed that shear hands already started to form
at moderate strains in a matrix of pre-existing microbands and were composed
of fine, slightly elongated subgrains (fragments). These hands propagated
along a similar macroscopic path and the subgrains, present within their
substructure, were rotated relative to the surrounding matrix about axes
approximately parallel to the sample radial and transverse directions for
deformation in torsion and PSC, respectively. The suhgrain boundaries were
largely observed to be non-crystallographic, suggesting that the subgrains
generally formed via multiple slip processes. Shear bands appeared to form
through a co-operative nucleation of originally isolated subgrains that
gradually interconnected with the others to form long, thin bands that
subsequently thickened via the formation of new subgrains. The observed
small dimensions of the subgrains present within shear bands and their large
misorientations clearly indicate that these subgrains can serve as potent
nucleation sites for the formation of ultrafine grain structures during both
subsequent recrystallisation, as observed during the present PSC
experiments, and phase transformation.
145.
Cizek, P., F. Bai, et al. (2005). "EBSD study of the orientation
dependence of substructure characteristics in a model Fe-30 wt%Ni alloy
subjected to hot deformation." Journal of Microscopy 217(2):
138-151.
The aim of the present investigation was to determine the orientation
dependence of substructure characteristics in an austenitic Fe-30wt%Ni model
alloy subjected to hot plane strain compression. Deformation was carried out
at a temperature of 950 degrees C using a strain rate of 10 s-1 to
equivalent strain levels of approximately 0.2, 0.4, 0.6 and 0.8. The
specimens obtained were analysed using a fully automatic electron
back-scatter diffraction technique. The crystallographic texture was
characterized for all the strain levels studied and the sub-grain structure
was quantified in detail at a strain of 0.4. The substructure
characteristics displayed pronounced orientation dependence. The major
texture components, namely the copper, S, brass, Goss and rotated Goss,
generally contained one or two prominent families of parallel larger-angle
extended subboundaries, the traces of which on the longitudinal viewing
plane appeared systematically aligned along the {111} slip plane traces,
bounding long microbands subdivided into slightly elongated subgrains by
short lower-angle transverse sub-boundaries. Relatively rare cube-orientated
grains displayed pronounced subdivision into coarse deformation bands
containing large, low-misorientated subgrains. The misorientation vectors
across subboundaries largely showed a tendency to cluster around the sample
transverse direction. Apart from the rotated Goss texture component, the
stored energy levels for the remaining components were principally
consistent with the corresponding Taylor factor values.
146.
Cizek, P., J. A. Whiteman, et al. (2003). EBSD study of the hot deformation
microstructure characteristics of a type 316L austenitic stainless steel.
Electron Microscopy and Analysis 2003. Institute of Physics Electron
Microscopy and Analysis Group Conference, Oxford, UK, Inst. of Phys.
Publishing Ltd.
Characteristics of the crystallographic texture and deformation
microstructure were studied in a type 316L austenitic stainless steel,
deformed in rolling at 900 degrees C to true strains of about 0.3 and 0.7,
using electron backscatter diffraction (EBSD). The texture was mainly
characterised by rotations towards the alpha fibre orientations with
increasing strain. At the lower strain level, there was considerable
evidence of a rotation of the pre-existing twin boundaries from their
original orientation relationship, as well as the formation of highly
distorted grain boundary regions and deformation bands. The subgrains were
predominantly arranged in elongated bands, the boundaries of which
frequently approximated to traces of the {111} slip planes. The
corresponding misorientations were generally small and largely displayed a
non-cumulative character across the band widths, while displaying a tendency
to cumulate strongly along the band lengths. Misorientation axis vectors
appeared non-crystallographic and were largely clustered around the
macroscopic transverse direction. At the higher strain level, general
characteristics of the deformation microstructure remained qualitatively
similar to those observed at the lower strain. However, the subgrain
dimensions became finer, the corresponding misorientation angles increased
and both these characteristics became less dependent on a particular grain
orientation. The extended sub-boundaries largely appeared to maintain an
approximately constant inclination towards the rolling plane within the
strain interval used. The obtained statistically representative data will
assist in the development of physically-based models of microstructural
evolution during hot deformation of austenitic stainless steels.
147.
Cizek, P., J. A. Whiteman, et al. (2004). "EBSD and TEM investigation
of the hot deformation substructure characteristics of a type 316L
austenitic stainless steel." Journal of Microscopy 213(Pt 3):
285-295.
The evolution of crystallographic texture and deformation substructure was
studied in a type 316L austenitic stainless steel, deformed in rolling at
900 degrees C to true strain levels of about 0.3 and 0.7. Electron
backscatter diffraction (EBSD) and transmission electron microscopy (TEM)
were used in the investigation and a comparison of the substructural
characteristics obtained by these techniques was made. At the lower strain
level, the deformation substructure observed by EBSD appeared to be rather
poorly developed. There was considerable evidence of a rotation of the
pre-existing twin boundaries from their original orientation relationship,
as well as the formation of highly distorted grain boundary regions. In TEM,
at this strain level, the substructure was more clearly revealed, although
it appeared rather inhomogeneously developed from grain to grain. The
subgrains were frequently elongated and their boundaries often approximated
to traces of 111 slip planes. The corresponding misorientations were small
and largely displayed a non-cumulative character. At the larger strain, the
substructure within most grains became well developed and the corresponding
misorientations increased. This resulted in better detection of
sub-boundaries by EBSD, although the percentage of indexing slightly
decreased. TEM revealed splitting of some sub-boundaries to form fine
microbands, as well as the localized formation of microshear bands. The
substructural characteristics observed by EBSD, in particular at the larger
strain, generally appeared to compare well with those obtained using TEM.
With increased strain level, the mean subgrain size became finer, the
corresponding mean misorientation angle increased and both these
characteristics became less dependent on a particular grain orientation. The
statistically representative data obtained will assist in the development of
physically based models of microstructural evolution during thermomechanical
processing of austenitic stainless steels.
148.
Clarebrough, L. M. and C. T. Forwood (1980). "The Properties of a Near
Sigma-9 Grain-Boundary.1. Analysis of Intrinsic Structure and Interaction
with Lattice Dislocations." Physica Status Solidi A 58(2):
597-607.
149.
Clarebrough, L. M. and C. T. Forwood (1988). "Burgers Vectors of
Secondary Grain-Boundary Dislocations in a Σ-3 Boundary in
α-Iron." Physica Status Solidi A 105(1): 131-138.
150.
Clarke, A. P., F. J. Humphreys, et al. (2003). Lattice Rotations at Large
Second-Phase Particles in Polycrystalline Aluminum. Thermec' 2003,
Leganés, Madrid, Spain, Trans Tech Publications Ltd.
The inhomogeneous deformation which occurs in the vicinity of large (>/=
2µm) second-phase constituent particles in AA1050
(Al-0.4wt%Fe-0.25wt%Si) and Al-2wt%Cu alloys during cold rolling has been
investigated using High Resolution Electron Backscattered Diffraction. The
maiximum misorientation angle, the axis of misorientation and the size of
the deformation zone have been measured as a function of strain, grain
orientation and particle size and shape. It was found that the maximum
misorientation angle within the deformation zone increased with strain, and
that the size of the deformation zone remained constant at approximately one
particle diameter. It was also found that the misorientation axis tended
towards alignment with the transverse direction as strain increases. Crystal
plasticity finite element modelling has demonstrated misoriented bands
adjacent to the particles of similar geometry, although their shapes are
found to be highly dependent on the starting orientation of the
crystal.
151.
Claus, J., G. Borchardt, et al. (1996). "Combination of EBSP
measurements and SIMS to study crystallographic orientation dependence of
diffusivities in a polycrystalline material: Oxygen tracer diffusion in
La2-xSrxCuO4±δ."
Materials Science and Engineering B 38(3): 251-257.
In the present work we demonstrate that electron back scattering pattern
(EBSP) measurements together with secondary ion mass spectrometry (SIMS) can
be used to study the crystallographic orientation dependence of tracer
diffusivities in polycrystalline materials. The crystal orientation of
single grains was determined with a dedicated scanning electron microscope
in the EBSP mode. 18O isotope depth profiles obtained in a subsequent tracer
diffusion experiment were measured by SIMS on single grains with known
orientation. The experiments yielded oxygen tracer diffusivities as a
function of crystal orientation, temperature and strontium concentration for
La2-xSrxCuO4±δ (x = 0 and 0.15) between
600 and 900 °C. A strong anisotropy of the oxygen diffusivity for the
investigated dopant concentrations was found.
152.
Claves, S. R. (2005). Evolution of aluminum iron silicide intermetallic
particles during homogenization of aluminum alloy 6063, Lehigh University.
PhD: 235.
As-cast 6xxx aluminum alloys contain
β-Al9Fe2Si2 intermetallic particles
that form at grain boundaries and interdendritic regions during
solidification. This secondary phase has a considerable negative influence
on the workability of the material during subsequent deformation processing;
e.g. it has been linked to the extrusion pick-up defect. To lessen its
deleterious effects, β-Al9Fe2Si2 is
transformed to α-Al8Fe2Si during the
homogenization process, a typical heat treatment cycle at 540--580°C for
6--8 hours.The scientific objective of this Ph.D. research was to increase
the understanding of morphological, chemical, and crystallographic aspects
of the β- to α-AlFeSi phase transformation. The two AlFeSi phases
differ in size, shape, color, chemical composition, crystal structure, and
bonding strength with the surrounding aluminum matrix. Various microscopy
(optical and electron) techniques have been employed to examine these
particle characteristics. This research investigates the particles'
evolution during intermediate heat treatment conditions.Light optical
microscopy was used to study the size, color, and two-dimensional shapes of
AlFeSi particles. As homogenization progresses, microstructures contain
long, charcoal-colored needles
(β-Al9Fe2Si2), which slowly transform
to shorter, gray spheroids (α-Al8Fe2Si).
Backscatter electron imaging in the scanning electron microscope was used
for higher magnification micrographs and more detailed particle
measurements.Due to the complex morphologies of the AlFeSi particles, planar
imaging was insufficient to accurately describe their shape.
Three-dimensional microstructures were obtained via serial sectioning
performed on a dual-beam focused ion beam instrument. Particle-matrix
interfaces from sequential images were extracted and compiled into
isosurfaces. α-spheroids possess much lower surface area-to-volume
ratios than β-platelets. For intermediate homogenization times, the
α-phase was found to nucleate on the sides and grow at the expense of
the β-particles, which shrink lengthwise. The α-phase eventually
encapsulates the ends of the plates making them rounded, with a thin middle
region.To confirm morphological-based AlFeSi phase predictions, specific
particles were identified via chemical composition using energy dispersive
spectroscopy. As homogenization proceeds, Si diffuses away from the
β-AlFeSi; the Fe:Si ratio increases until the microstructure contains
strictly α-particles. Intermetallics were also identified via
crystallography, using electron backscatter diffraction. The thin dimension
of β-platelets corresponds to the c-axis of the monoclinic unit
cell.
153.
Clement, N., A. Lenain, et al. (2005). Characterization of the Interactions
Between Recrystallization and Precipitation in a Two Phase β-Metastable
Titanium Alloy. Solid to Solid Phase Transformations in Inorganic Materials
2005, Phoenix, Arizona, USA, TMS.
Thanks to their high performance to density ratio, b-metastable titanium
alloys are more and more used for several applications. Indeed, a large
range of microstructures and resulting properties can be obtained at the end
of controlled thermomechanical processing. The objective of the present work
was to study the interactions and competition between precipitation and
recrystallization in the Ti-LCB alloy. SEM and EBSD-OIM were used to
characterize the precipitation and recrystallization processes after
different thermomechanical treatments. The higher driving force for phase
transformation leads to a faster precipitation that completely saturates the
potential nucleation sites for β recrystallization, thus stabilizing
the deformed substructure of th β grains.
154.
Cleton, F., P. H. Jouneau, et al. (1999). "Crystallographic orientation
assessment by electron backscattered diffraction." Scanning
21(4): 232-237.
With an angular orientation accuracy of at least 1 degrees, the ability of
electron backscattered diffraction (EBSD) to determine and emphasise
crystallographic orientation is illustrated. Using the abilities of
specially developed software for computing Euler angles derived from the
scanned specimen, misorientations are pointed out with acceptable
flexibility and graphic output through crystallographic orientation maps or
pole figures. This ability is displayed in the particular case of laser
cladding of nickel-based superalloy, a process that combines the advantages
of a near net-shape manufacturing and a close control of the solidification
microstructure (E-LMF: epitaxial laser metal forming).
155.
Coates, D. G. (1967). "Kikuchi-like relflection patterns observed in
the SEM." Philosophical Magazine 16: 1179-84.
156.
Cola, M. J., V. R. Dave, et al. (2004). "Grain Boundary Character in
Alloy 690 and Ductility-Dip Cracking Susceptibility." Welding Journal
83(1): 1S - 5S.
A complete elucidation of the physical mechanisms responsible for
intermediate temperature ductility loss in metals (ductility dip) is
elusive. This article provides insight pertaining to ductilitydip cracking
in Alloy 690, namely that the fraction and interconnectivity of low-energy
coincidence site lattice grain boundaries have a pronounced effect on
material susceptibility to ductility-dip cracking. In this work, as-received
wrought Alloy 690 is compared to Alloy 690 that was strain annealed to
achieve a different configuration of special boundaries. Hot ductility tests
are performed using a Gleeble trademark thermomechanical simulator. It is
shown that the intermediate temperature ductility dip is less pronounced in
the strain-annealed material, that it is shifted toward lower temperatures,
and that the on-cooling ductility recovery temperature (DRT) is higher.
Scanning electron microscope fractographic analysis is coupled with electron
backscattered diffraction (EBSD) pattern analysis to provide a preliminary
metallurgical explanation of this improvement. It is qualitatively shown
that improving the topological connectivity of these special boundaries in
Alloy 690 enhances material resistance to cracking. Although this current
study does not examine all possible factors contributing to ductility-dip
cracking (DDC), it does suggest that grain boundary character and
specifically the topological connectivity of special boundaries are
important but, previously, not widely appreciated microstructural
influencing factors in DDC.
157.
Collazo, R., S. Mita, et al. (2005). Polarity control of LP-MOVPE GaN using
N2 as the carrier gas. 2005 Materials Research Society Fall
Meeting, Boston, Massachusetts, USA.
The polarity control of GaN films grown on c-plane sapphire substrates by
LP-MOVPE using N2 as carrier and diluent gas was investigated in
detail. The polarity type depended on the substrate preparation prior to the
high temperature (HT) GaN growth. Device-quality Ga-polar GaN was obtained
by using a low temperature (LT) AlN buffer layer followed by a specific
annealing process. Optimized buffer layer thickness was 10 nm, with an
annealing time of 20 min and a temperature of 1050As EBSD h C. By using
these conditions for the buffer layer growth, mirror-like Ga-polarity GaN
was grown using a V/III ratio of 100. The full width at half maximum (FWHM)
of Ga-polar GaN films was 360 arcsec for the symmetric (00.2) reflection and
640 arcsec for the skew-symmetric (30.2) reflection. The surface roughness
was measured by AFM to be 0.2 nm RMS and the growth rate was estimated at
2.0 µm/hr. These results indicated that by exclusively using
N2 carrier gas, one can achieve films of the same quality as
those more commonly grown by using H2 carrier gas.
158.
Collins, M. G., J. C. Lippold, et al. (2004). "An investigation of
ductility-dip cracking in nickel-based weld metals - Part III." Welding
Journal 83(2): 39S-49S.
In Part I of this investigation of ductility-dip cracking (DDC) in
nickel-based filler materials, the strain-to-fracture (STF) test (Ref. 1)
was used to quantify the DDC susceptibility of two Ni-based filler metals,
Filler Metal 52 and Filler Metal 82. Ductility-dip cracking susceptibility
was related to the nature of the migrated grain boundaries in these weld
metal deposits and the effect of grain boundary "tortuosity" on
the mechanical locking of these boundaries at elevated temperature. Part II
of this investigation used scanning electron microscopy to examine the DDC
fracture surfaces in order to relate fracture mode to temperature,
composition, interstitial content (hydrogen), and microstructure. Part III
of this investigation uses optical microscopy, high-resolution scanning
electron microscopy, and electron backscattered diffraction (EBSD)
techniques to further explore the factors that contribute to DDC in Ni-based
weld metals. Based on this analysis and the results from Parts I and II of
this investigation, a DDC mechanism is described that involves the complex
interplay of alloy composition, interstitial and impurity element additions,
grain boundary segregation, triple-point grain boundary junctions, grain
growth, grain boundary sliding, precipitation, recrystallization, boundary
orientation relative to the applied strain, and the contribution of grain
boundary misorientation and accumulated local strain. Insight is provided to
optimize elevated-temperature ductility in order to avoid DDC in Ni-based
weld deposits and other austenitic alloys.
159.
Conway, P., Z. Huang, et al. (2004). Characterisation of Intermetallics and
Mechanical Behaviour in the Reaction between SnAgCu and Sn-Pb Solder Alloys.
Proceedings of the Sixth IEEE CPMT Conference on High Density Microsystem
Design and Packaging and Component Failure Analysis, HDP'04, Shanghai,
China.
The multicomponent material behavior and possible formation of intermetallic
precipitates during reactions between Sn-Pb and Sn-Ag-Cu Pb free alloys were
discussed using thermodynamic calculations. It was found that two Sn-Ag-Cu
alloys namely Sn-3.9Ag-0.6Cu and Sn-3.0Ag-0.5Cu were selected to react with
different contamination levels of eutectic Sn-37Pb solder. The data for
nanoindenter penetration depth versus time available during the 1800 seconds
dwell period under constant load was used to analyze the creep behavior of
the β-Sn. Analysis shows that the Pb rich phase exhibits slightly lower
hardness and modulus than the β-Sn at RT and an extremely low hardness.
(Edited abstract)
160.
Cornen, M. and R. L. Gall (2004). Measurement of Impurity Concentration at
Grain Boundaries after Recrystallization. Second Joint International
Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M,
Annecy, France, Trans Tech Publications Ltd.
161.
Cornen, M. and R. Le Gall (2004). Direct measurement of impurity segregation
concentration at grain boundaries for polycrystalline materials using EBSD
and 3D reconstruction of SEM images of Etch grooves. Interfacial Engineering
for Optical Properties III, San Francisco, California, USA, Materials
Research Society.
Impurity segregation at grain boundaries in polycrystalline alloys is known
to have a tremendous impact on the material properties such as mobility,
cohesion. But, direct measurement of grain boundary chemistry is quite
complex and there are quite few results concerning polycrystals. In this
paper we present an indirect method to measure segregationmisorientation
dependence on polycrystalline Ni-S alloys using both EBSD and 3D
reconstruction of etch grooves. Samples of Ni-S alloy (7.2 ppm at) have been
annealed at different temperatures to get equilibrium segregation at grain
boundaries. Then they have been etched near the transpassive potential to
form etch grooves, whose geometry depends on the sulfur segregation level.
Grain boundaries misorientation statistics and first results about the
segregation-misorientation function are given here.
162.
Coronel, V. F. and D. N. Beshers (1988). "Magnetomechanical Damping in
Iron." Journal of Applied Physics 64(4): 2006-2015.
163.
Cosandey, F. (1997). High Spatial Resolution EBSD Study of Nanosized
Epitaxial Particles. Microscopy and Microanalysis, Cleveland, Ohio,
Springer.
164.
Cosandey, F. and T. E. Madey (2001). "Growth, Morphology, Interfacial
Effect and Catalytic Properties of Au on TiO2." Surface
Review and Letters 8(1-2): 73-93.
165.
Cosandey, F., L. Zhang, et al. (1999). Epitaxial Orientation Determination
of Nanosized Particles by EBSD. Microscopy and Microanalysis, Portland,
Oregon, Springer-Verlag.
166.
Cosandey, F., L. Zhang, et al. (2001). "Effect of substrate temperature
on the epitaxial growth of Au on TiO2(1 1 0)." Surface
Science 474: 1-13.
167.
Cosandey, F., P. Markodeya Raj, et al. (1999). Texture Determination Of
Ceramic Materials By EBSD. Microscopy and Microanalysis, Portland, Oregon,
Springer-Verlag.
168.
Cosandey, F., R. Persaud, et al. (1997). "Growth and epitaxy of Au on
TiO2(110)." Structure and Evolution of Surfaces. Symposium.
Mater. Res. Soc.
The growth of Au on TiO2(110) has been examined by high
resolution field emission scanning electron microscopy (HRSEM) in
combination with electron backscattered diffraction (EBSD). The Au was
evaporated under UHV conditions onto stoichiometric TiO2(110)
surfaces in the temperature range from 300 to 475 K. At 300 K and for low
coverages (<1.5 nm), Au grows as discrete particles. For thicker
coverages (>1.5 nm), the particles coalesce to form a network, but
percolation is absent even after deposition of 5 nm Au. Upon annealing or
deposition (>or=5 nm) at 475 K, the particles appear clearly faceted and
are oriented along specific crystallographic directions. EBST patterns taken
from individual particles reveal two equivalent domain orientations rotated
by 180 degrees with epitaxial orientation relationships corresponding to
(111)Au||(110)TiO and
110Au||001(TiO2) (orientation I) and
110Au||001(TiO2) (orientation II). (8
References).
169.
Cosandey, F., X. Liu, et al. (2005). "Single-crystal-like materials by
the self-assembly of cube-shaped lead zirconate titanate (PZT)
microcrystals." Langmuir 21(8): 3207-3212.
We demonstrated the formation of single-crystal-like materials that contain
preferentially oriented arrays of lead zirconate titanate (PZT) cube-shaped
particles by self-assembly. Hydrothermally synthesized PZT particles with a
bulk composition of Zr/Ti = 70/30 were used in making microcrystal arrays.
Spreading a. suspension containing PZT cube-shaped particles, 2-propanol,
and mineral oil at the air-water interface produced a one-dimensional planar
array of PZT particles on the water surface. The array so formed was
subsequently transferred onto a flat or curved substrate. X-ray diffraction
and electron backscattered diffraction analyses revealed that most of the
cube-shaped particles in the array were oriented with their pseudocubic
(001) direction aligned parallel to the normal direction of the substrate
surface. Filling the arrays with matrixes produced monolayer or multilayer
textured composites. The piezoelectric properties of oriented cube-shaped
micron-sized particles in the self-assembled arrays were measured using a
modified atomic force microscope to reveal the ferroelectric nature of the
PZT arrays. Copyright 2005 American Chemical Society.
170.
Cotrina, E., A. Iza-Mendia, et al. (2004). "Study of the Ferrite Grain
Coarsening behind the Transformation Front by Electron Backscattered
Diffraction Techniques." Metallurgical and Materials Transactions A
35A(1): 93-102A.
The degree of ferrite grain refinement that can be reached in low-carbon
microalloyed steels by thermomechanical processing is limited, to a certain
extent by the grain coarsening which can take place behind the
transformation front. The coarsening of ferrite grains is the result of two
different mechanisms: elimination of ferrite grains produced by normal grain
growth after full impingement on the austenite grain boundary plane and/or
coalescence between different ferrite grains with close orientation formed
from the same crystallographic variant. The lack of experimental data to
support either process is due to the experimental difficulties encountered
when analyzing the phenomenon. Some transmission electron microscope (TEM)
observations reveal that the ferrite grains formed along a prior grain
boundary in deformed austenite are separated by a mixture of low and high
angle grain boundaries upon impingement. In the present work, the electron
backscattered diffraction (EBSD) technique has been applied to investigate
the microstructural evolution during transformation with special emphasis
placed on the alpha - alpha grain boundary character as a means of
investigating the contribution of coalescence/grain growth to
coarsening.
171.
Cotrina, E., B. Lopez, et al. (2003). Influence of thermomechanical
treatment on the austenite-pearlite transformation in a high carbon
Nb-microalloyed steel. Symposium on the Thermodynamics, Kinetics,
Characterization and Modeling of: Austenite Formation and Decomposition
2003, Chicago, Illinois, Minerals, Metals and Materials Society
(TMS).
Multipass torsion tests were carried out with a Nb-microalloyed high carbon
steel, using different deformation sequences in order to modify the
austenite state prior to transformation. Both recrystallized and deformed
austenite microstructures were investigated. After deformation different
cooling rates were applied. The Electron Back Scattering Diffraction (EBSD)
technique was applied to study the pearlite microstructure. The ferritic
'orientation unit' was defined using a tolerance criterion of a 15 deg
change in orientation. Lambda good correlation was observed between the
units identified in this way and the cleavage facets measured from the
fracture profiles in SEM. The results show that accumulating strain in the
austenite before transformation does not affect the interlamellar spacing
when similar cooling conditions are applied, but significantly refines the
orientation unit.
172.
Cotrina, E., I. Gutierrez, et al. (2004). "Study of the gamma-alpha
transformation in microalloyed steels by EBSD techniques." Revista de
Metalurgia (Madrid) 40(5): 359-364.
The degree of ferrite grain refinement that can be reached in low carbon
microalloyed steels by thermomechanical processing can be limited.
Simultaneously, grain coarsening takes place, which leads to a coarser grain
size than that corresponding to the initial nucleation density. Coarsening
of ferrite grains can be due to different mechanisms: elimination of ferrite
grains produced by normal grain growth and coalescence between neighbour
ferrite grains with close orientation. In order to investigate the
contribution of both mechanisms, EBSD technique has been applied making
special emphasis on the study of the alpha-alpha grain boundary
character.
173.
Courtas, S., L. Dumas, et al. (2003). Interactions between the conditions of
copper electrodeposition and the density of hillocks. Copper Interconnects,
New Contact Metallurgies/Structures, and Low-k Interlevel Dielectrics II:
Proceedings of the International Symposium, Orlando, Florida, USA, The
Electrochemical Society, Inc.
The influence of the rotational speed of the wafer and the current density
during the electroplating on the grain size, the impurity content, and the
texture of 1.3µm copper films has been studied. The most interesting
result is that the properties of the electroplated films affect the hillock
density. It has been proposed that a more stable film after plating leads to
lower structural rearrangement during the etch top layer deposition and thus
decrease the hillock density.
174.
Crampon, J. (1981). "Creep Mechanisms of Fine-Grained
Magnesium-Oxide." Annales de Chime-Science des Materiaux 6 (1):
82-90.
175.
Crawford, D. C. and G. S. Was (1991). "Grain-Boundary Character
Distributions in Ni-16Cr-9Fe Using Selected Area Channeling Patterns -
Methodology and Results." Journal of Electron Microscopy Technique
19(3): 345-360.
176.
Crawford, D. C. and G. S. Was (1992). "The Role of Grain-Boundary
Misorientation in Intergranular Cracking of Ni-16Cr-9Fe in 360-Degrees-C
Argon and High-Purity Water." Metallurgical Transactions A
23(4): 1195-1206.
177.
Crooks, R., Z. Wang, et al. (1998). "Microtexture, microstructure and
plastic anisotropy of AA2195." Materials Science and Engineering
A257: 145-152.
178.
Cross, I. and V. Randle (2003). "Lowest angle solution versus low-index
axis solution for misorientations." Scripta Materialia 48:
1587-1591.
A study of misorientation distributions in recrystallised high- strength IF
steel has compared both the disorientation (lowest angle) solution and
nearest low-index axis solution. It is shown that consideration of the
lowest-angle misorientation distribution alone provides an incomplete and
ambiguous distribution of nearest low-index misorientation axes.
179.
Cross, I. J., V. Randle, et al. (1999). Microtexture development in high
strength interstitial free steels. Twelfth International Conference on
Textures of Materials (ICOTOM 12), McGill University, Montreal, Canada, NRC
Research Press.
180.
Crowder, M. A., Y. Mitani, et al. (2003). "Parametric investigation of
SLS-processed poly-silicon thin films for TFT applications." Thin Solid
Films 427(1-2): 101-107.
The sequential lateral solidification (SLS) process has been used to
crystallize thin a-Si films on quartz for thin-film transistor (TFT)
applications. In this study, we have focused on the two-shot SLS
microstructure, with parametric variation of the laser fluence (through the
range of the SLS process window), the film thickness (250, 500, and 1000
A-thick a-Si), and the laser pulse duration (FWHM of 30, 90, and 180 ns).
Following the SLS crystallization, the microstructure and orientation of the
films were examined using SEM and EBSD, respectively. TFTs were fabricated
in parallel to these microstructural investigations to correlate the
electrical properties. Variation of the film thickness seems to have the
largest effect on device performance: average mobility values of similar to
288 cm2 V-1 s-1, similar to 176
cm2 V-1 s-1, and similar to 104
cm2 V-1 s-1 were seen for TFTs fabricated
on 1000, 500, and 250 A-thick Si films. Other varied parameters had only
minor effects on the TFT characteristics. Copyright 2002 Elsevier Science
B.V. All rights reserved
181.
Cruz, F., F. Caleyo, et al. (1995). "Semiautomatic Measurement of
Individual Orientation of Crystals by Using Etch Pits and Digitized
Images." Materials Characterization 34(3): 189-194.
182.
Cruz, L. R., A. L. Pinto, et al. (2005). Characterization of CSS deposited
CdTe films by electron back-scatter diffraction technique. Conference Record
of the Thirty-First IEEE Photovoltaic Specialists Conference, Lake Buena
Vista, Florida, USA, IEEE.
The properties of a material are affected by the orientations of individual
grains, that is, by its microtexture. Microtexture can be determined in a
scanning electron microscope by analyzing the electron back-scatter
diffraction patterns provided by the specimen. This work focuses upon
microtexture determination in cadmium telluride thin films deposited by
close spaced sublimation. The texture of individual grains, the
misorientation between grains, and coincident site lattice boundary maps
were obtained, showing that electron back-scatter diffraction is a useful
technique for investigating grain boundary features in these films.
183.
Cruz-Gandarilla, F., F. C. Cereijo, et al. (1998). "Crystallographic
Texture." Revista Mexicana de Fisca 44(3): 222-230.
184.
Cruz-Gandarilla, F., R. Penelle, et al. (2005). A study of local
microstructure and texture heterogeneities in a CGO Fe3%Si alloy from hot
rolling to primary recrystallization. Textures of Materials - ICOTOM 14,
Leuven, Belgium, Trans Tech Publications.
The Goss texture developed after secondary recrystallization in Conventional
Grain Oriented (C.G.O.) silicon steels allows minimization of power losses
in transformer cores. The mechanisms of formation and evolution of Goss
grains from the hot rolling stage up to the primary recrystallized state are
not still well clarified.
This work deals with characterization of the local microstructure and
texture heterogeneities by scanning electron microscopy (SEM), X-ray
diffraction (XRD) and Electron Back Scattered Diffraction (EBSD). A detailed
study of the microstructure shows that grains form a band structure
decorated by thin carbides strings or lamellae found through the sheet
thickness.
The main texture components determined by XRD are the α and γ
fibers, the {001} <u v w> and the Goss orientations. A large variation
in their volume fraction is observed at different sheet thickness in the
sample and at different stages of the thermomechanical process. It is worthy
to note that the Goss grains lying at the quarter of the sheet thickness are
present either as bands parallel to the rolling direction at the early stage
of processing route (hot rolled state) or within the {111} <112>
grains for the subsequent steps.
185.
Cruz-Gandarilla, F., T. Baudin, et al. (2004). Study of Local Microstructure
and Texture Heterogeneities in Hot Rolled CGO Fe-3%Si Sheets. Second Joint
International Conference on Recrystallization and Grain Growth, ReX &
GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
After secondary recrystallization, the Fe-3%Si alloys, grade Conventional
Grain Oriented (C.G.O.), exhibit a Goss texture that is sought for
minimizing watt losses in transformer cores. The mechanisms of Goss grain
formation and their evolution during the processing route from hot rolling
to decarburizing such as the early first steps of abnormal growth are not
still well cleared up. This work deals with the influence of local
microstructure and texture heterogeneities observed by X-ray diffraction
(XRD) and Electron Back Scattered Diffraction (EBSD) at the hot rolling
step. The present results complete those previously obtained by neutron
diffraction. Presence of Goss grain colonies at about the quarter of the hot
rolled sheet is probably, as it has already been suggested, at the origin of
the Goss grain presence at the primary recrystallized state.
186.
Cruz-Gandarilla, F., T. Baudin, et al. (2006). "Characterization of
global and local textures in hot rolled CGO Fe3%Si." Materials Science
Forum 509: 25-30.
The present work is an attempt to understand the recrystallisation
mechanisms in Fe-3% Si alloys used in transformer cores. After secondary
recrystallisation silicon steels exhibit a Goss texture with a more or less
important spread depending on the details of the processing route, namely,
conventional grain orientation CGO or high permeability Hi-B. The mechanisms
of Goss grain formation during hot rolling and primary recrystallisation, as
well as those controlling the first steps of abnormal growth, are not yet
well understood. The present work mainly deals with texture characterization
of the hot rolled state. Surface, quarter and half thickness samples are
prepared from hot-rolled sheet. Global and local textures are characterized
by neutron diffraction and electron backscattered diffraction, respectively.
The orientation distribution functions and the volume fraction of the
different texture components are calculated. The components from global
texture measurements are (001)Ý1-10¨, (112)Ý1-10¨
(alpha fiber), (011)Ý100¨ (Goss) and (111)Ý1-21¨ (111)
Ý1-10¨(g fiber). EBSD measurements have shown large variations of
texture from the surface to the half thickness of the sheet. These local
measurements are related to the global results by rotation about the
transverse direction. Moreover, the grain size appears to be inhomogeneous.
187.
Cunha, M. A. d. and S. C. Paolinelli (2004). Evolution of Non-Oriented
Silicon Steel Texture on Recrystallization and Grain Growth. Second Joint
International Conference on Recrystallization and Grain Growth, ReX &
GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
The evolution of annealing texture of non-oriented grain silicon steel as a
function of annealing temperature was investigated from hot rolled samples
taken from industrial production. Hot band samples were annealed at
900°C, cold rolled to final thickness of 0.5 mm in a single stage cold
rolling process or in two stages with intermediate annealing at 900°C,
and final annealed in the temperature range from 540°C to 980°C. The
results showed that the [001] //RD fibre is an important recrystallization
texture component, but it may be consumed by further grain growth and become
a minor component. The effect of grain growth in the temperature range
investigated seems to be that of strengthening the main components at the
expense of the others. The results suggest that to avoid the reduction of
the [001] //RD fibre on grain growth, a volume fraction ratio between the
texture components (111)[112] and (110)[001] close to unity is necessary
after recrystallization.This can be obtained under conditions that enhance
[001] //RD fibre on recrystallization, such as: strong [111]ND fibre in the
deformation texture, large initial grain size and enhanced grain boundary
mobility, by proper composition and purity.
188.
Cunningham, B. and K. H. G. Ashbee (1990). "An Insitu SEM Kossel
X-Ray-Diffraction Study of Pseudoelasticity." Acta Metallurgica et
Materialia 38(12): 2561-2565.
189.
Czerwiec, T., H. He, et al. (2003). "Reactive magnetron sputtering as a
way to improve the knowledge of metastable f.c.c. nitrogen solid solutions
formed during plasma assisted nitriding of Inconel 690." Surface and
Coatings Technology 174-175: 131-138.
Low temperature plasma assisted nitriding (PAN) treatments of Inconel 690 (a
nickel base alloy with a 30 wt.% chromium content) produce a complex layer
constituted by two different metastable f.c.c. solid solutions denoted
(γN1 and γ N2). In addition, different
layer thicknesses are observed for differently oriented grains. Reactive
magnetron sputtering (RMS) of Inconel 690 in argon–nitrogen containing
mixtures is used to produce homogeneous films constituted by a well defined
gN phase. In reactive conditions, the as-deposited coatings (T<100°C)
containing up to 30 at.% of nitrogen are nanocrystalline supersaturated
f.c.c. solid solution (γN) with a grain size lying between 3 and 7.5
nm. A comparison between the products synthesized by these two techniques
(PAN and RMS) is presented in this study. The formation of γ N phases
in low temperature PAN is discussed in the light of electron backscatter
diffraction measurements and by comparison with X-ray diffraction patterns
of RMS coatings. By using the results obtained in situ by RMS on heated
substrates and by tempering of as-deposited films, the decomposition
products of the γN phase at high temperature (greater than or equal to
450°C) or long PAN treatments at 400°C are identified to be f.c.c.
CrN and γ(Ni,Fe) depleted in nitrogen.
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