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33 records found
1.
Iamboliev, T., S. Katayama, et al. (2002). Formation Mechanism of Rapidly
Quenched Microstructure of Laser Weld Metals in Austenitic Stainless Steels.
Trends in Welding Research: Proceedings of the 6th International Conference,
Phoenix, Arizona, USA.
Microstructural characteristics and the relationship between cellular
dendritic growth direction and crystal orientation were investigated in
laser weld fusion zones of austenitic stainless steels through optical
microscopy observation and electron backscattered diffraction patters
analyses. Type 310S was confirmed to be solidified as an austenitic single
phase of cellular dendritic growth with the <100> preferred
orientation in any weld metals, and grains in weld fusion zones grew
epitaxially from the HAZ. On the other hand, in Type 304, lacy, skeletal or
globular ferritic microstructure to nearly fully austenitic structure were
observed depending on pulse duration, or solidification and cooling rates.
In the case of normal solidification, growth direction of cellular dendrites
was in good agreement with the <100> orientation of not austenite but
ferrite phase, where K-S relationship existed between the ferrite and
austenite phases. Similarly, during rapid solidification, fully austenitic
structure was observed, the number of austenite grains increased, and the
growth direction of cells did not correspond with the <100>
orientation of austenite phase. It is consequently revealed that fully
austenitic microstructure of rapidly solidified Type 304 steel was formed
not as a result of metastably or massively austenitic solidification but due
to the ferrite-to-austenite solid-state transformation after the primary
ferrite solidification.
2.
Ibarra, A., A. Iza-Mendia, et al. (2004). "Influence of
thermo-mechanical processing on the microstructure of Cu-based shape memory
alloys produced by powder metallurgy." Materials Science and
Engineering A 378(1-2 (Special Issue)): 263-268.
Cu-Al-Ni shape memory alloys processed by powder metallurgy show very good
thermo-mechanical properties, much better than those found in alloys
produced by conventional casting. In this paper, we present the
microstructural characterisation of these powder metallurgy alloys in order
to find the microscopic mechanisms, linked to the powder metallurgy
processing method, which are indeed responsible of such good
thermo-mechanical behaviour. Electron microscopy studies scanning electron
microscopy (SEM), electron backscatter diffraction (EBSD) and transmission
electron microscopy (TEM) show that powder metallurgy processing creates a
sub-grain structure characterised by the presence of low angle
sub-boundaries. These sub-boundaries are found to be lying on {1 1 0} and {1
1 2} lattice planes and are composed by an arrangement of superdislocations.
These sub-boundaries may improve ductility in two ways: acting as a sink of
dislocations which promotes plastic deformation and decreasing stress
concentration at grain boundaries. Moreover, since sub-boundaries act as
weak obstacles for the movement of martensite plates, the improvement on
ductility is accomplished by an adequate thermo-mechanical behaviour.
Copyright 2004 Published by Elsevier B.V.
3.
Ichikawa, M. and K. Hayakawa (1982). "Micro-Probe Reflection
High-Energy Electron-Diffraction Technique.1. Determination of
Crystallographic Orientations of Polycrystal-Silicon Surfaces."
Japanese Journal of Applied Physics Part 1 21(1): 145-153.
4.
Ichinohe, Y., H. Ishii, et al. (1996). "Site-Specific Characteristic of
the Kikuchi-Like Bands in High-Angular-Resolution X-Ray Photoelectron
Diffraction." Japanese Journal of Applied Physics Part 2 35(5A):
L587-L590.
5.
Ihara, K. and Y. Miura (2004). "Dynamic recrystallization in Al-Mg-Sc
alloys." Materials Science and Engineering A 387-389:
647-650.
The main research interest was to investigate the mechanisms in the
restoration process of Al–3 mass% Mg and Al–3 mass% Mg–0.2
mass% Sc alloy containing second-phase Al3Sc precipitates. The alloy
specimen, Al–3% Mg–0.2% Sc, was peak-aged, where it contained
stable coherent, spherical Al3Sc precipitates with an average diameter of
0.2 m and a volume fraction of 0.005. The main techniques utilized are
compression tests, optical microscopy, the Laue X-ray method, the electron
backscattering pattern method using a scanning electron microscopy and
transmission electron microscopy (TEM). The observed fluctuation of the
stress–strain curves and grain growth during high temperature
deformation strongly suggested the occurrence of dynamic recrystallization
during hot deformation of the alloy. The transmission Laue method revealed
new undeformed spots formed during deformation, which directly shows that
new grains have been generated. TEM observation revealed the areas of high
dislocation density at the immediate vicinity of the particles in hot
deformed conditions. In the ternary alloy (Al–3% Mg–0.2% Sc),
dynamic recrystallization seems to occur more frequently than in the binary
alloys (Al–3% Mg) through grain boundary bulging. These observations
lead to a hypothesis that dynamically recrystallized grains in the present
study were nucleated by the combined effects of stress induced grain
boundary bulging and preferential hardening at the sites of Al3Sc
precipitates near grain boundaries.
6.
Ihara, K. and Y. Miura (2004). "Dynamic recrystallization in Al-single
crystals revealed by synchrotron radiation Laue technique." Materials
Science and Engineering A 387-389: 651-654.
An experimental study on the microstructure development and
stress–strain behavior during high temperature deformation of aluminum
(Al) single crystals was made by using the synchrotron radiation Laue
technique and the electron backscatter pattern technique. The main purpose
was to clarify the process of dynamic recrystallization (DRX). The measured
stress–strain curves with large stress peaks and the in situ observed
new Laue spots without streaks at around the stress peaks confirmed the
occurrence of DRX. Crystallographic analysis shows that the common axis
between the DRX grain and the matrix is close to <1 1 2>. The
unrecrystallized region near the DRX grain consists of subgrains adjoined
each other with <1 1 2> tilt boundaries and the size of subgrains
becomes smaller and the misfit at subgrain boundaries becomes larger as the
DRX grain boundaries are approached. These experimental results suggest that
DRX grains are nucleated through the development of subgrains.
7.
Ikuhara, Y. (2001). "Grain-Boundary and Interface Structures in
Ceramics." Journal of the Ceramic Society of Japan 109(7):
S110-S120.
8.
Iliescu, D., Ian Baker, et al. (2004). "Determining the Orientations of
Ice Crystals Using Electron Backscatter Patterns." Microscopy Research
and Technique 63: 183-187.
Knowing the orientations of the ice crystals in a polycrystalline aggregate
is essential for understanding and modeling the flow of naturally occurring
ice. Here we show, for the first time, that the orientation of crystals in
polycrystalline ice can be determined with a higher angular and spatial
resolution and more rapidly than any currently used method by using electron
backscatter patterns (EBSPs) in a cold-stage equipped scanning electron
microscope. We also present an orientation image map constructed from EBSPs,
and discuss possible applications of the technique for ice. The results
indicate that obtaining EBSPs and orientation images from other frozen
water-containing materials, such as clathrate hydrates, may also be
possible.
9.
Ilievski, D., P. Austin, et al. (2003). "Studies into the Internal
Structure of Gibbsite Agglomerates." Chemical Engineering Technology
26(3): 363-368.
10.
Imamura, T., Y. Hayakawa, et al. (2002). Formation Mechanism of
Recrystallization Nuclei in Polycrystalline a-Fe. ICOTOM 13, Seoul, Korea,
Trans Tech Publications Inc.
Cold rolling texture of polycrystalline 3%Si-Fe were investigated using
high-resolution Electron Backscattered Diffraction (EBSD) method. From the
measurement, there are deformation bands with {12 4 1}<014> in a
deformed grain. It turned out that the orientation relationship between
deformation bands and surrounding deformed grain can be explained by the
orientation rotation caused by the activation of the slip system which has a
common slip plane with an adjacent grain. {12 4 1}<014> orientation
was one of the major components in the recrystallized texture. A hypothesis
that recrystallization nuclei is generated directly from the deformation
bands formed by an activation of the slip system that has a common slip
plane of neighboring deformed grains was proposed from the present
experimental results.
11.
Imamura, T., Y. Hayakawa, et al. (2003). "Observation of Cold-Rolling
Texture and Partially Recrystallixed Texture in Polycrystalline 3 pct Si-Fe
by High-Resolution Electron Backscattered Diffraction." Metallurgical
and Materials Transactions A 34A(No. 2): 403-408.
Cold-rolling texture and partially recrystallized texture of polycrystalline
3 pct Si-Fe were investigated using high-resolution electron backscattered
diffraction (EBSD) method. From the measurement on a deformed grain with
{211}<011> ~ {111}<011> orientations, deformation bands with {12
4 1}<014> orientation were found. It turned out that the orientation
rotation relationship betwen deformation bands and surrounding deformed
grain can be explained by the activation of the slip system, which has a
common slip plane with an adjacent grain. Oriented nucleation of
recrystallized grains with {12 4 1}<014> orientation was observed in a
deformed grain with {211}<011 ~ {111}<011> orientation. Exactly the
same orientation relationship that was observed between deformed grain and
the deformation bands was also observed between the deformed grain and the
recrystallized grain. A hypothesis that recrystallization nuclei are
generated directly from the deformation bands formed by an activation of the
slip system that has a common slip plane of neighboring deformed grains was
proposed from the present experimental results.
12.
Imayev, R. M., O. A. Kaibyshev, et al. (1992). "Mechanical-Behavior of
Fine-Grained TiAl Intermetallic Compound.2. Ductile-Brittle
Transition." Acta Metallurgica et Materialia 40(3):
589-595.
13.
Imayev, R. M., O. A. Kaybyshev, et al. (1991). "Mechanical-Properties
of Fine-Grain TiAl Intermetallide.2. Brittle-Tough Transition." Fizika
Metallov I Metallovedenie(3): 179-187.
14.
Inagaki, H. (2005). "Recent Progress and Related Problems in Texture
Investigations -Problems and Limitations in Taylor's Model." Journal of
the Japan Institute of Metals 69(3): 283-290.
Recent trends in the field of texture investigations are briefly reviewed.
ODF and EBSP analyses have made most significant contribution to the
progress in the texture investigations. Owing to the development of these
two experimental techniques, we can now not only quantitatively evaluate
textures of various materials, but also we can directly correlate the
distribution of main texture components with the observed microstructures.
As to the theoretical investigations, the development of rolling textures of
various metals has been intensively studied by using Taylor's model. In this
paper, the validity of the basic assumption of the homogeneous deformation
adopted in this model is critically examined in detail. All metallographic
observations made on cold rolled pure Fe and Al do not support this
assumption. It is strongly suggested that dislocation substructures
developed during cold rolling strongly affect the development of cold
rolling textures.
15.
Inagaki, H. and A. Umezawa (2005). Origins of Cube Recrystallization Texures
in Heavily Rolled High Purity Al. Textures of Materials - ICOTOM 14, Leuven,
Belgium, Trans Tech Publications.
In high purity (4N) Al containing 50 ppm Cu, very strong cube textures can
be developed by cold rolling 98 % and annealing at 500 ºC. The
orientation density in this material amounted to as much as 220 times
random, i. e. about 3 times stronger than that observed in standard 4N Al.
It is expected that the origins of cube textures should be most
unambiguously clarified by using this material. Commercial hot bands of this
materials were cold rolled 98 % to the thickness of 132 μm and
isothermally annealed at 230 ºC. Detailed EBSP analyses were made both
on the rolling plane and on the longitudinal section at each stage of
annealing. It was found that in the hot band of this high purity Al, cube
orientations were mostly rotated away into other orientations due to low
temperature hot rolling with high rolling reductions. Therefore, regions
having cube orientations were very few. They were not present in the form of
so called cube bands, which had been reported in previous investigations,
but in the form of isolated, rather equi-axed recrystallized grains. After
98 % cold rolling, these remaining cube regions were fragmented, and further
rotated away into other orientations, so that only very few cube oriented
regions were observed in the cold rolled materials. However, it was from
such deformed cube oriented regions that the most potential exact cube
recrystallized grains were formed. They were nucleated much earlier and grew
much faster than grains of other orientations.
16.
Inagaki, H. and A. Umezawa (2006). "Formation of cube recrystallized
grains in high-purity Al." Materials Research and Advanced Techniques
97(1): 49-58.
In high-purity 4 N (99.99 wt.%) Al containing 50 wt.ppm Cu, very strong
[100] &;lt;001&;gt; recrystallization textures are developed after
98% cold rolling and annealing at 500 C. They are about three times stronger
than those observed in standard high-purity 4 N Al without Cu addition. In
this paper, the mechanism of the formation of such strong
[100]}&;lt;001&;gt; recrystallization textures were investigated in
detail by using the EBSP (electron backscatter pattern) analysis. It was
found that, at the earliest stage of
recrystallization,[100]&;lt;001&;gt;-recrystallized grains were
nucleated by forming a row lying parallel to the rolling direction and
growing preferentially within the elongated deformed grain in which they
were nucleated. Most of these [100]&;lt;001&;gt;-recrystallized
grains had orientations very near to the exact cube
orientations.[100]&;lt;001&;gt;-recrystallized grains in this
materials were characterized by their rapid growth, which was observed at
the later stages of recrystallization. Since they were surrounded by
deformed regions having very strong {beta}-fiber rolling textures formed by
heavy cold rolling, their grain boundaries were high-angle grain boundaries
with high mobility. Assisted further by high stored energy introduced by
heavy rolling reductions,[100]&;lt;001&;gt;-recrystallized grains
could grow very rapidly, traversing readily several deformed grains. In this
material,[100]&;lt;001&;gt;-recrystallized grains were not nucleated
so abundantly. However,[100]&;lt;001&;gt;-recrystallized grains were
nucleated much earlier and grew much faster than recrystallized grains with
other orientations. They were, therefore, always larger than recrystallized
grains with other orientations. Due to such size advantages,
[100]&;lt;001&;gt;-recrystallized grains could rapidly consume
fine-recrystallized grains with other orientations during the subsequent
grain growth process. As a result, microstructures observed after annealing
at 500 C for 2 h consisted mostly of coarse [100],
&;lt;001&;gt;-recrystallized grains slightly misoriented with each
other. It is, thus, rapid growth of few
[100]&;lt;001&;gt;-recrystallized grains during recrystallization,
and their preferential grain growth, that enhance the development of very
strong [100]}&;lt;001&;gt; recrystallization textures in this
high-purity Al. Cu seems to suppress nucleation of recrystallized grains
with other orientations.
17.
Inokuti, Y., H. Morita, et al. (2003). "Twin Morphology Formed on Goss
Si-steel Single Crystal." Journal of the Iron and Steel Institute of
Japan 89(6): 686-690.
The twin morphology of Goss single crystal of silicon steel was investigated
using electron back scattering diffraction (EBSD) method of FESEM, and was
compared with that of FE-SEM. The orientation analysis parallel to ND, RD
and TD showed a very narrow band of about 3 mu m width perpendicular to the
rolling direction. The twin formed between the boundary of the Goss single
crystal matrix and the very narrow band. This boundary showed step-like
morphologies of about 70-200 nm. The angle between the two (110)
orientations of the (211) twin was 70,5 deg. The origin of twin due to the
alternate formation of twin boundary was also observed, It is suspected that
this permitted to do the formation energy of twin as low as
possible.
18.
Inoue, H., M. Ishio, et al. (2002). Texture and Shape Memory Effect of TiNi
Alloy Produced from Ti/Ni Laminated Sheets. ICOTOM 13, Seoul, Korea, Trans
Tech Publications Inc.
We have developed new processing to produce thin TiNi alloy sheets. This
processing is composed of repetitive roll-bonding for making a Ti/Ni
laminated sheet from Ti and Ni, and of subsequent heat treatment for leading
to reactive diffusion. The Ti/Ni laminated sheet changed to a nearly single
TiNi phase material throgh the formation of Ti2Ni and
Ni3Ti intermetallc phases by solid phase reaction. The TiNi sheet
consisted of a near <111>//ND texture such as {223}<110> in the
B2 parent phase. Planar anisotropy of shape memory strain was not pronounced
in this material due to an isotropic character of the {111}<uvw>
texture. The formation of such texture by reactive diffusion has been
discussed in view of texture inheritance.
19.
Irvine, J. and T. N. Baker (1984). "The Influence of Rolling Variables
on the Strengthening Mechanisms Operating in Niobium Steels." Materials
Science and Engineering 64(1): 123-134.
20.
Isabell, T. C. and P. E. Fischione (2000). Plasma Cleaning for Electron
Microscopy. 7th Asia-Pacific Electron Microscopy Conference, Singapore,
Times Publishing Group.
21.
Isabell, T. C. and V. P. Dravid (1997). Electron Backscattered Diffraction
(EBSD) with a Cold Field Emission Gun (cFEG) SEM: Resolution, Sensitivity
and Applications. Microscopy and Microanalysis 1997, Cleveland, Ohio,
Springer.
22.
Isabell, T. C. and V. P. Dravid (1997). "Resolution and sensitivity of
electron backscattered diffraction in a cold field emission gun SEM."
Ultramicroscopy 67(1-4): 59-68.
The tradeoff between sensitivity and spatial resolution is inherent in all
analytical techniques. Electron backscattered diffraction (EBSD) in a
scanning electron microscope (SEM) is no exception, and determining this
tradeoff for EBSD is the focus of this contribution. Because the specimen is
tilted in EBSD (typically at 70 degree), the spatial resolution needs to be
defined with respect to three orthogonal directions; as lateral resolution
(within the specimen plane but normal to beam direction), longitudinal
resolution (within the specimen plane but parallel to beam direction) and
depth resolution (extent of depth information). The significance of these
different resolution criteria becomes relevant for interface analysis, and
is demonstrated using a variety of materials systems and electron-optical
parameters. The sensitivity of EBSD is directly related to the ability of
backscattered electrons (BSEs) to produce sufficient contrast in the Kikuchi
pattern at the recording medium (phosphor in our case). The various
parameters which govern the sensitivity of EBSD are discussed with the help
of experimental analysis. It is argued that EBSD/OIM is a viable technique
even in a cold field emission gun SEM, where there is less absolute current
available and stability of current is less than for other electron sources.
(Author abstract) [References: 20]
23.
Ishihara, R., M. He, et al. (2005). Electrical property of coincidence site
lattice grain boundary in location--controlled Si island by excimer--laser
crystallization. International Conference on Polycrystalline
Semiconductors-Materials, Technologies, Device Applications,
Switzerland.
Two-dimensional location control of large Si grains by, so-called,
μ-Czochralski process with excimer-laser crystallization enables
formation of thin-film transistors inside a grain; single-grain Si TFTs. In
this study, the effect was studied of remaining defects inside the
location-controlled grains on the electrical performance of single-grain Si
TFTs. From electron backscattering diffraction analysis, it was found that
most of the defects inside the location-controlled grains are coincidence
site lattice (CSL) boundary of Σ3, followed by Σ9 and Σ27. If
such CSL boundary is parallel to the current flow direction, the field
effect mobility of the TFT is 597 cm2/Vs. When the Σ9
boundary is perpendicular to the current flow, the mobility decreases to 360
cm2/Vs, suggesting electrical activity in the Σ9 boundary.
24.
Ishii, H., J. D. Mun, et al. (1996). "Faceted voids and grain
orientation at solid state diffusion bonded interfaces between Cu and single
crystal cubic ZrO2." Materials Science Forum 207-209(pt 1):
253-256.
We have investigated the morphology of the non-reactive solid state
diffusion bonded interfaces between polycrystalline copper and single
crystal zirconia of (100) and (110) orientations. The bonded interfaces
showed regular faceted voids on the Cu side. The angles of the faceted void
edges to the left bracket 001 right bracket direction of the ZrO2 is
dependent on the crystallographic orientation of the ZrO2. To examine the
relationship between the Cu grains that showed faceted voids and the ZrO2,
the orientation of the Cu grains were measured using Electron Back
Scattering Diffraction (EBSD) in the scanning electron microscope. These
misorientations are shown in a Frank-Rodrigues map and the dependence on
bonding conditions is discussed. (Author abstract) [References: 5]
25.
Ishimoto, S., K. Nogita, et al. (2004). "Crystallography of zirconium
hydrides in recrystallized zircaloy-2 fuel cladding by electron backscatter
diffraction." Journal of Nuclear Science and Technology 41(7):
731-740.
Precipitation morphology and habit planes of the δ-phase Zr hydrides,
which were precipitated within the α-phase matrix grains and along the
grain boundaries of recrystallized Zircaloy-2 cladding tube, have been
examined by electron backscatter diffraction (EBSD). Radially-oriented
hydrides, induced by residual tensile stress, precipitated in the outside
region of the cladding, and circumferentially-oriented hydrides in the
stress-free middle region of the cladding. The most common crystallographic
relationship for both types of the hydrides precipitated at the inter- and
intra-granular sites was identical at (0001)α // {111
}δ, with {101-7}α // {111
}δ being the occasional exception only for the
intergranular radial hydrides. When tensile stress was loaded, the
intra-granular hydrides tended to preferentially precipitate in the grains
with circumferential basal, pole textures. The inter-granular hydrides
tended to preferentially precipitate on the grain faces opposite to tensile
axis. The change of prioritization in the precipitation sites for the
hydrides due to tensile stress could be explained in terms of the relaxation
effect of constrained elastic energy on the terminal solid solubility of
hydrogen at hydride precipitation.
26.
Islamgaliev, R., R. Valiev, et al. (2004). "Microstructural aspects of
superplasticity in the 1420 and 1421 aluminum alloys." JOM
56(11): 220.
Various temperatures of equal-channel angular pressing (ECAP) were applied
to commercial aluminum alloys 1420 and 1421 for grain refinement. The
microstructures were examined using transmission electron microscopy (TEM),
energy-dispersion analysis (EDS) and electron back scattering diffraction
(EBSD). Special attention was paid to investigations of structure evolution
during in-situ heating in column of microscope up to temperature of
superplastic deformation. It was found that microstructure of the ECAP
samples at room temperature consisted of both the equiaxed grains with
mainly high angle grain boundaries and precipitates of various phase
composition (Al2LiMg, AlLi, Al3Zr). Small tensile specimens (gage section
1x2.5x5 mm3 and 1x1x0.3 mm3) were sectioned along the length the billets by
electrospark machining. Tensile testing showed these materials are
superplastic at temperature 400 orphology C with elongations 1500-1600% at
strain rates 10-2-10-1 c-1. The difference between microstructure and
superplastic properties of specimens processed at various ECAP temperatures
340-420oC is considered. Microstructural aspects of superplasticity in
ultrafine-grained aluminum alloys are discussed.
27.
Ito, K., T. Hayashi, et al. (2003). Oxidation Behavior of Mo-based Alloys
Coated with Silicide Using the Halide-activated Pack Cementation Method.
Thermec' 2003, Leganés, Madrid, Spain, Trans Tech Publications
Ltd.
This article summarizes recent progress in research on oxidation behavior of
pack-cemented Mo-9Si-18B alloys with a Mo5SiB2/Mo
two-phase eutectic microstructure. The deposited layer of as-cemented
Mo-9Si-18B alloy consists of MoSi2. Upon heating to temperatures
above 1500° C, the deposited layer is transformed into B-doped
Mo5Si3 through a reaction between the deposited layer and the
matrix containing B. Steady-state oxidation is observed at 1300 - 1500°
C and its rates are almost equal to those of MoSi2. No
significant increase in weight loss was observed in a short-term cyclic
oxidation test, since the columnar structure with orientation preference in
B-doped Mo5Si3 coating layer must be reduced thermal stress in
the cyclic oxidation test.
28.
Ito, K., T. Hayashi, et al. (2005). "Oxidation Protective Silicide
Coating on Mo-Si-B Alloys." Metallurgical and Materials Transactions A
36A(3): 627-636.
A MoSi2coating was successfully formed on a Mo-9Si-18B alloy,
consisting of Mo5SiB2 (T2) and Mo solid
solution (Moss) phases, using pack cementation with Si.
Isothermal and cyclic oxidation tests of pack-cemented Mo-9Si-18B alloys
were performed at 1300 °C and 1500 °C. Steady-state oxidation rates
at both temperatures are almost equal to those of pure MoSi2. The
MoSi2 layer is completely transformed into
Mo5Si3 (T1) containing B after oxidation at
1500 °C for 24 hours. Thermal expansion of the T1 phase is
anisotropic, but a [001] texture in the growth direction for the columnar
grains in the T1 layer reduces thermal stresses generated around
the phases. Evolution of T1 layers during oxidation between 1300
°C and 1500 °C was investigated; their growth rate constants and the
interdiffusion coefficient of Mo and Si in the Mo-Si-B system have been
evaluated and compared with those in the binary Mo-Si system. Furthermore,
we have studied phase transformations in a simpler system MoSi2
vs T2using MoSi2/T2 diffusion couples.
Layers of T1 and MoB + T1 were formed in the diffusion
zone during oxidation at temperatures between 1400 °C and 1600 °C.
This behavior is different from that of the pack-cemented Mo-9Si-18B alloy.
Pack-cemented T2 single crystals show a diffusion structure
similar to that of MoSi2/T2 diffusion couples, but the
ratio of layer thickness is different. Based on these diffusion results, a
method for extending the lifetime of the MoSi2 layer is
proposed.
29.
Ivanisenko, Y., R. Z. Valiev, et al. (2005). "Grain boundary statistics
in nano-structured iron produced by high pressure torsion." Materials
Science and Engineering A 390(1-2): 159-165.
The microstructure and the spectrum of grain boundary misorientations were
studied in Armco iron, following high pressure torsion (HPT) deformation, by
means of transmission electron microscopy (TEM) and orientation imaging
microscopy (OIM). It was found that HPT deformation results in the formation
of an equiaxed grain structure with a mean grain size of 270 and 130nm using
a shear strain of γ =210 and 420, respectively. The misorientation
spectra in HPT iron have a bimodal character with maxima in low (at 1-2
degrees) as well as in high misorientation angle ranges. A marked increase
in the fraction of special boundaries (Σ 3- Σ 45) was revealed
as a result of HPT. The microstructural changes due to HPT are discussed and
compared with those obtained during conventional deformation modes.
30.
Ivanov, I. and A. Kolics (2005). On compensation of copper crystallographic
orientation effect in CoWP electroless deposition. 208th Meeting of The
Electrochemical Society, Los Angeles, California, USA.
As IC interconnect minimum line width continues to shrink the
crystallographic orientation of dual damascene Cu grains, their size change
dramatically from a highly textured (111) films with large grains to a
randomly oriented small grains1. High density of interface
boundaries and vacancies in a small line or via results in reduced stress
migration reliability and increased Cu resistivity due to accumulated
residual impurities from copper electroplating. One of the methods to
improve Cu interconnect electromigration and stress migration is a
deposition of a self-aligned conductive CoWP cap on Cu pattern immediately
after CMP process in a standard dual damascene process with blanket
dielectric barrier and etch stop.2 However, the use of a Co alloy
cap can also provide the additional advantage of a complete elimination of a
dielectric barrier with relatively high k-value thus improving
Keff of interlayer dielectric stack, increasing available thermal
budget, and reducing cost of 1C manufacturing by reducing number of process
steps. The CoWP conductive self-aligned cap is deposited using an
electroless deposition process directly onto post-CMP Cu surface without Pd
activation but with prior in-situ removal of atmospheric and post-CMP
cleaning residues using aqueous solutions with a controlled concentration of
dissolved gases such as oxygen or CO2. Several CoWP deposition
chemistries have been developed and the differences in CoWP film morphology
as a function of Cu grain orientation were studied using AFM, EBSD, and
electrochemical methods. Co and W reduction and DMAB / hypophosphite
oxidation partial reactions were studied at various temperatures using CoWP
electroless processes from ammonia and TMAH-based formulations. The role of
stabilizing agents and some organic additives on initiation and deposition
processes and resulting film properties were also investigated. It was found
that a significant surface roughness of CoWP deposited from
NH3-based formulation (Fig.1) can be reduced by at least an order
of magnitude by deposition of a CoWP film from a recently developed
tetramethylammonium-based formulation. The effect of O2
concentration during copper preclean in the production process chamber was
evaluated (Fig. 3) and optimum ambient was selected to minimize the Cu
surface roughness before CoWP deposition.
31.
Ivanov, I. and A. Kolics (2005). On compensation of copper crystallographic
orientation effect in CoWP electroless deposition. 208th Meeting of The
Electrochemical Society, Los Angeles, California, USA.
As IC interconnect minimum line width continues to shrink the
crystallographic orientation of dual damascene Cu grains, their size change
dramatically from a highly textured (111) films with large grains to a
randomly oriented small grains1. High density of interface
boundaries and vacancies in a small line or via results in reduced stress
migration reliability and increased Cu resistivity due to accumulated
residual impurities from copper electroplating. One of the methods to
improve Cu interconnect electromigration and stress migration is a
deposition of a self-aligned conductive CoWP cap on Cu pattern immediately
after CMP process in a standard dual damascene process with blanket
dielectric barrier and etch stop.2 However, the use of a Co alloy
cap can also provide the additional advantage of a complete elimination of a
dielectric barrier with relatively high k-value thus improving
Keff of interlayer dielectric stack, increasing available thermal
budget, and reducing cost of 1C manufacturing by reducing number of process
steps. The CoWP conductive self-aligned cap is deposited using an
electroless deposition process directly onto post-CMP Cu surface without Pd
activation but with prior in-situ removal of atmospheric and post-CMP
cleaning residues using aqueous solutions with a controlled concentration of
dissolved gases such as oxygen or CO2. Several CoWP deposition
chemistries have been developed and the differences in CoWP film morphology
as a function of Cu grain orientation were studied using AFM, EBSD, and
electrochemical methods. Co and W reduction and DMAB / hypophosphite
oxidation partial reactions were studied at various temperatures using CoWP
electroless processes from ammonia and TMAH-based formulations. The role of
stabilizing agents and some organic additives on initiation and deposition
processes and resulting film properties were also investigated. It was found
that a significant surface roughness of CoWP deposited from
NH3-based formulation (Fig.1) can be reduced by at least an order
of magnitude by deposition of a CoWP film from a recently developed
tetramethylammonium-based formulation. The effect of O2
concentration during copper preclean in the production process chamber was
evaluated (Fig. 3) and optimum ambient was selected to minimize the Cu
surface roughness before CoWP deposition.
32.
Ivanov, V. A., D. A. Molodov, et al. (2004). On the Effect of “Surface
Triple Junction” on Grain Boundary Motion. Second Joint International
Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M,
Annecy, France, Trans Tech Publications Ltd.
33.
Iza-Mendia, A., M. L. No, et al. (2003). "Electron microscopy study of
microtexture in Cu-Al-Ni shape memory alloys processed by powder
metallurgy." Journal De Physique IV 112(I): 615-618.
Cu-Al-Ni shape memory alloys processed by powder metallurgy show very good
thermomechanical properties, being the mechanical behavior similar to the
one observed in single crystals. In this paper we present the
microstructural characterization of a sample elaborated by powder metallurgy
in two different stages of the process: after being compacted by Hot
Isostatic Pressing (HIP) and after compaction and hot rolling, in order to
find the microscopic mechanisms responsible of their mechanical behavior.
The characterization has been carried out by means of Scanning Electron
Microscopy using Backscattered Electron Imaging (SEM-BSE) and Electron
BackScattered Diffraction (EBSD), as well as Transmission Electron
Microscopy (TEM).
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