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73 records found
1.
Paccard, D., J. Allemand, et al. (2004). "Structural characterization of NdNi(1-x)Cuxcompounds." Journal of Alloys and Compounds 381(1-2): 63-65.
Phase transformations and crystal structures in the ternary compounds NdNi(1-x/)Cux were examined with x parameter variation from 0 to 0.3 using X-ray diffraction on powders and single crystals. Three phases were characterized: an orthorhombic CrB type for x values between 0 and 0.175, a new monoclinic variant of the CrB type for x values ranging from 0.175 to 0.20, an orthorhombic FeB type for x values larger than 0.20. The unit cell parameters of the monoclinic variant (space group Pm, Z=16, α=7.603(1), b=8.732(4), c=11.146(3) Å, ß=109.91(2)°) are related to the orthorhombic CrB type parameters by the relations am=2a, bm=2c, cm=b-a
2.
Paik, J.-M., K.-C. Park, et al. (2004). "Relationship between Grain Structures and Texture of Damascene Cu Lines."
Journal of Electronic Materials 33(1): 48-52.
Th anistropic spread of the central peak in a (111) pole figure by X-ray diffraction (XRD) was observed for damascene Cu lines of 0.18-2 µm in width and 0.5 µm in depth. The spread originates from the existence of slightly tilted (111) grains because of inclined sidewalls. The tilted (111) orientation is favorable only for polygranular clusters whose sidewall energies can be minimzied simultaneously. Consequently, bamboo grains have an exact <111> orientation, while the polygranular clusters have a tilted <111> orientation. Using this concept, the volume fraction of the bamboo grains and polygranular clusters in the damascene Cu lines were quantified using the XRD pole plots.
3.
Paillard, P., T. Baudin, et al. (1994). "Recrystallization texture in Fe 3% Si alloys obtained by direct casting: characterization by EBSD and x-ray diffraction." Materials Science Forum 157-6(pt 1): 1027-1032.
A recrystallization study has been performed in electrical Fe Si 3% alloys containing solute elements as tin, copper or manganese obtained by direct casting between two rolls. After annealings at different temperature under dry hydrogen of cold rolled samples, the texture function was calculated from data obtained by X ray diffraction or Electron BackScattered Diffraction (EBSD) depending on the grain size. The evolution of the different texture components were studied according to reduction amounts (cold rolling), annealing temperature and solute elements. The cubic texture has been observed for some samples. (Author abstract) [References: 10]
4.
Palumbo (1998). Applied Nanocrystalline Materials. Toronto, Ontario Hydro.
5.
Palumbo, G. (1997). Grain Boundary Engineering, Ontario Hydro.
6.
Palumbo, G., E. M. Lehockey, et al. (1996). Grain boundary engineering for intergranular fracture and creep resistance. Mocroscopy and Microanalysis 1996. J. M. C. G. W. Bailey, R. V. W. Dimlich, J. R. Michael, N. J. Zaluzec. San Francisco, San Francisco Press, Inc.: 348-9.
7.
Palumbo, G., E. M. Lehockey, et al. (1997). Application of Microdiffraction in SEM for Assessing Intrinsic Materials Susceptibility to Intergranular Corrosion and Stress Corrosion Cracking. Microscopy and Microanalysis 1997, Cleveland, Ohio, Springer.
8.
Palumbo, G., E. M. Lehockey, et al. (1998). "Overview: Applications for Grain Boundary Engineered Matrials." JOM 50(2): 40-3.
9.
Pan, Y., B. L. Adams, et al. (1996). "Grain Boundary Structure Effects on Intergranular Stress Corrosion Cracking of Alloy X-750." Acta Materialia 44(12): 4685-4694.
It is well known that the properties and behavior of grain boundaries are strongly affected by local chemistry and atomic structure. This paper focuses on the mesoscale description of grain boundary structure (i.e. the five crystallographic degrees of freedom) and correlations with intergranular stress corrosion cracking observed in Alloy X-750. Orientation imaging microscopy, coupled with serial polishing, is used to reveal mesoscale structure and the connectivity of the grain boundary network. The propensity for cracking is correlated with the coincident site lattice (CSL) classification of grain boundary geometry, coupled with information about the orientation of the grain boundary plane. The data is interpreted to show that low-CSL boundaries (defined by the more restrictive Palumbo-Aust criterion), low-angle boundaries, and general boundaries with plane normals well of the principal stress axis, have low vulnerability to cracking.
10.
Pan, Y., T. Olson, et al. (1995). "Applications of Orientation Imaging Analysis to Microstructural Control of Intergranular Stress Corrosion Cracking." Canadian Metallurgical Quarterly 34(3): 147-154.
11.
Panchanadeeswaran, S. and D. P. Field (1995). "Texture Evolution During Plane Strain Deformation of Aluminum." Acta Metallurgica et Materialia(43): 1683-1692.
12.
Panchanadeeswaran, S., R. D. Doherty, et al. (1996). "Direct Observation of Orientation Change by Channel Die Compression of Polycrystalline Aluminum - Use of a Split Sample." Acta Materialia 44(3): 1233-1262.
The orientation changes of a set of grains in a 2 × 2 mm region on an "internal" surface of a two-part polycrystalline aluminum sample were measured by the Backscattered Kikuchi Diffraction (BKD) technique before and after 40% height reduction in a channel die. Bulk textures determined by both BKD and X-ray diffraction showed moderate agreement with predictions from a rate dependent, Taylor like, polycrystal model. However, the predicted local orientation changes agreed with the experiments for only a few of the 58 grains studied. In most cases, the average orientation change was different in magnitude and direction from this prediction. The observations also showed large in-grain misorientations sometimes as large as 25°, while the model assumes a single orientation for each grain. Although the orientations of many grains were along the rolling texture fiber after deformation, they were not at the positions predicted by the model. Thus homogeneous uniform strain, a common assumption in deformation texture models cannot be used to predict structural changes at grain level.
13.
Pang, Y. and P. Wynblatt (2006). "Effects of Nb Doping and Segregation on the Grain Boundary Plane Distribution in TiO2." Journal of the American Ceramic Society 89(2): 666-671.
Orientation imaging microscopy has been used to investigate the effects of Nb doping on the grain boundary plane distributions in TiO2 (rutile). By comparing the grain boundary plane distribution of the undoped material with theoretical estimates of grain boundary energy anisotropy of pure rutile, it is possible to show that the frequency of grain boundary planes is inversely correlated with grain boundary energy. In the case of Nb-doped material, this inverse correlation can also be demonstrated by a comparison of grain boundary plane frequency with measurements of surface energy anisotropy. In addition, by comparing the grain boundary plane distribution of doped and undoped materials with previous measurements of Nb grain boundary segregation in TiO2 as a function of grain boundary plane orientation, it is possible to explain the changes in grain boundary plane distribution which result from doping.
14.
Pantleon, W. (2004). Resolving Orientation Correlations in Deformation Structures by EBSD. Interfacial Engineering for Optical Properties III, San Francisco, California, USA, Materials Research Society.
For visualization of orientation inhomogeneities in crystalline material orientation imaging maps are conventionally used, with different colors representing different orientations. Two different approaches are proposed to extract more information from the orientation data on deformation structures gathered by electron back-scattering diffraction. First, a statistical approach is introduced for obtaining the chord length distribution of a grain structure and, secondly, an evaluation scheme is presented to resolve the details of the deformation structure within individual grains.
15.
Pantleon, W. (2005). "Retrieving orientation correlations in deformation structures from orientation maps." Materials Science and Technology 21(12): 1392-1396.
Orientation information as obtained by electron back scattering diffraction in crystalline material is conventionally visualised in orientation maps with different colours representing different orientations. The possibility of resolving orientation inhomogeneities from such maps depends strongly on the selected colouring scheme. For gaining spatial information on the orientation distribution and retrieving orientation correlations within selected regions of an orientation map, an advanced evaluation scheme is presented. By determining the predominant rotation axis within individual grains of a deformed polycrystal and displaying the sign carrying disorientation angle, characteristic features of the deformation structure, as alternating orientation differences or orientation gradients, are resolved.
16.
Pantleon, W. (2005). Unbiased evaluation of chord length distributions from orientation maps. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
Grain structures in crystalline material are commonly identified by orientation inhomogeneities in orientation maps. A statistical approach is introduced to extract quantitative information on the chord length distribution of grains from orientation data gathered by electron back-scattering diffraction.
17.
Paransky, Y., A. Berner, et al. (1999). "Microstructure of Reaction Zone at the Ti-AlN Interface." Materials Letters 40(4): 180-186.
The phase composition of the reaction zone between Ti matrix and AlN particles was investigated using EPMA and electron backscatter diffraction techniques (EBSD) in SEM. The TiN (cubic, NaCl type), Ti3AlN (cubic, perovskite type) and Ti-rich Ti3Al (hexagonal, Ni3Sn type) phases were identified in the reaction zone after anneals at 900, 1000 and 1100° C. The binary nitride TiN and the ternary nitride Ti3AlN exhibit a complex interpenetrating morphology. A two-phase, Ti3AlN/Ti3Al, lamellar region was observed between the Ti3AlN and Ti3Al layers after annealing at 1000 and 1100 °C.
18.
Paransky, Y., A. Berner, et al. (2000). "Phase Recognition in AIN-Ti System by Energy-Dispersive Spectroscopy and Electron Backscatter Diffraction." Mikrochimica Acta 134(3-4): 171-177.
The combination of energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques in scanning electron microscope was employed to characterize the reacted interface between Ti matrix and AlN particles. Due to the high localization of EDS and EBSD, representative measurements of chemical composition and reliable determination of the crystal structurewere possible for each phase in the reaction zone with complex morphology. The TiN1-x (cubic, NaCl type), Ti3AlN (cubic, perovskite type) and Ti-rich Ti3Al (hexagonal, Ni3Sn type) phases were identified in the reaction zone after annealing at 1100°C. EDS+EBSD combination is an efficient tool for phase analysis at the interface in reactive multicomponent systems.
19.
Paransky, Y., I. Gotman, et al. (2000). "Reactive phase-formation at AlN-Ti and AlN-TiAl interfaces." Materials Science and Engineering A 277(1-2): 83-94.
Ti specimens with embedded AIN particles, as well as AlN-Ti and AlN-TiAl diffusion couples were annealed at 900 to 1100 degrees C for up to 40 h. The microstructure and phase composition of the reacted interfaces were characterized using electron probe x-ray microanalysis (EPMA) and electron backscatter diffraction (EBSD) in scanning electron microscope and x-ray diffraction (XRD). In AlN-TiAl diffusion couples, a ternary Ti2AlN compound was formed at the interface. A more complex AlN-TiN + Ti3AlN- Ti3Al-(Ti)(Al)-Ti reaction zone was observed at the AlN-Ti interface. The morphology of the two-phase (TiN + Ti3AlN) layer changed with time so that the ternary nitride dominated after longer exposures. The kinetics of the reaction zone growth was two-stage, with a significant decrease of the growth rate at the second stage. Such behavior is believed to be caused by the changing morphology of the (TiN + Ti3AlN) layer accompanied by decreasing diffusivity of the components. (C) 2000 Elsevier Science S.A. All rights reserved.
20.
Parisot, R., S. Forest, et al. (2000). "Modeling the mechanical behavior of a multicrystalline zinc coating on a hot-dip galvanized steel sheet." Computational Materials Science 19: 189-204.
Numerical simulations can play a major role in the understanding of deformation mechanisms in zinc coatings of galvanized steel sheets during forming processes. A three-dimensional finite element (FE) simulation of a thin zinc coating on a galvanized steel sheet has been performed taking the multicrystalline structure of the coating into account. Experimental characterization of the gauge length of a real in situ tensile specimen reveals 34 large flat zinc grains; the grain orientations are determined using the electron back-scatter diffraction (EBSD) technique. The geometry and orientation of the grains and the plastic deformation modes specific to hexagonal close-packed (hcp) metals as plastic slip and twinning are incorporated into the modeling using a classical crystal plasticity framework. The constraint effect of the substrate is evidenced by comparing the results to the computation of a zinc layer without substrate under the same loading conditions. Attention is then focused on, respectively, the initiation of plastic activity at the grain boundaries, the multiaxial stress state of the grains, the development of a strain gradient within the thickness.
21.
Parisot, R., S. Forest, et al. (2004). "Deformation and Damage Mechanisms of Zinc Coatings on Hot-Dip Galvanized Steel Sheets: Part 1. Deformation Modes." Metallurgical and Materials Transactions A 35A(3): 797-811.
Zinc-based coatings are widely used for protection against corrosion of steel-sheet products in the automotive industry. The objective of the present article is to investigate the deformation modes at work in three different microstructures of a thin (8µm) zinc coating on an interstitial-free steel substrate under tension, plane-strain tension and expansion loading. Damaged mechanisms are addressed in a companioin article. The plastic slip and twinning activities in the zinc grains of an untempered cold-rolled coating (labeled NSK), a tempered cold-rolled coating (labeled SK), and a recrystallized coating are compared with the response of the corresponding bulk low-alloyed zinc material. The in-plane grain size in the NSK and SK coatings ranges from 300 to 600µm, vs about 30µm in the recrystallized coating and bulk material. The coatings exhibit a strong crystallographic texture, with the c-axis generally normal to the sheet plane. Basal slip is shown to be the main derformation mechanism in bulk zinc and the recrystallized coating, wheras pyramidal pi2 slip and mechanical twinning are found to be major modes in the NSK and SL coatings. These results, obtained from an extensive, quantitative slip-line analysis combined with electron backscattered diffraction (EBSD) measurements, are explained by the constraining effect of the substrate. This effect is successfully modeled using a simple Taylor-like polycrystalline approach. The recrystallized coating behaves much like the bulk material. The interpretation of this grain size effect between the NSK and SK coating, on the one hand, and the recrystallized coating on the other hand, requires a full three-dimensional finite-element analysis of the multi-crystalline coating provided in this work. The simulations show that strong strain gradients can develop in the recrystallized coating from the interface to the surface, which is not the case in the NSK and SK coatings.
22.
Parisot, R., S. Forest, et al. (2004). "Deformation and Damage Mechanisms of Zinc Coatings on Hot-Dip Galvanized Steel Sheets: Part II. Damage Modes." Metallurgical and Materials Transactions A 35A(3): 813-823.
Zinc-based coatings are widely used for protection against corrosion of steel-sheet products in the automotive industry. The objective of the present article is to investigate the damage modes at work in three different microstructures of a zinc coating on an interstitial-free steel substrate under tension, plane-strain tension and expansion loading. Plastic-deformation mechanisms are addressed in a companioin article. Two main fracture mechanisms, namely intergranular cracking and transgranular cleavage fracture were identified in an untempered cold-rolled coating, a tempered cold-rolled coating and a recrystallized coating. No fracture at the interface of the steel and zinc coating was observed that could lead to spalling, in the studied zinc alloy. A complex network of cleavage cracks and their interaction with deformation twinning is shown to develop in the material. An extensive, quantitative analysis based on systematic image analysis provides the number and cumulative length of cleavage cracks at different strain levels for the three investigated microstructures and three loading conditions. Grain refinement by recrystallization is shown to lead to an improved cracking resistance of the coating. A model for crystallographic cleavage combining the stress component normal to the basal plane and the amount of plastic slip on the basal slip systems is proposed and identified from equibiaxial tension tests and electron backscattered diffraction (EBSD) analysis of the cracked grains. This analysis requires the computation of the nonlinear stress-strain response of each grain using a crystal-plasticity constitutive model. The model is then applied successfully to other loading conditions and is shown to account for the preferred orientations of damaged grains observed in the case of plane-strain tension.
23.
Park, C., G. Bruckner, et al. (2002). Orientation Relationships and Variant Selection during alpha- to gamma- Phase Transformation in Low Carbon Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
A direct crystallographic orientation comparison between a parent and product phase of a microalloyed low carbon steel during the diffusion controlled a to y transformation was investigated by use of EBSD in a field emission gun SEM. After a recrystallization anneal an orientation mapping was carried out on a marked area both in the ferritic and after the phase transformation at 920°C in the austenitic state. In order to stabilize the austenitic phase at ambient temperature, Ni-atoms by wrapping the sample in an austenitic stainless steel foil were enabled to diffuse into the specimen surface during phase transformation treatment. Through improved experimental methods and new analytical equipment, it is possible to identify a large number of transformed grains and them to get a better statistical reliability of the stabilized austenite orientation. The experimental results were compared with the orientation relationship predicted by the Bain, Kurdjumov-Sachs and Nishiyama-Wassermann model. It is also possible to observe variant selection, namely the lack of the {100}<110> orientation in the transformation texture, which mostly arises from {111}<112> and {554}<225> orientations in ferrite texture. At the early stages of phase transformation {110}<112> and {110}<110> oriented grains were developed directly adjacent to {111}<112> and {554}<225> grains in the ferrite phase. In this case always the same variant {110}<110> was selected. This observation serves to understand the variant selection in diffusion controlled phase transformations.
24.
Park, H. and D. N. Lee (2000). Deformation and Annealing Textures of a 90% Drawn Electrolytic Copper Wire. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
An electrolytic copper rod of 8mm in diameter was cold drawn to 90% reduction in area. The deformed wire had the major <111> + minor <100> duplex fiber texture, which changed to major <100> + minor <111> fiber texture after annealing at temperatures below 600°C for 3h. However, when annealed at 700°C, the annealing texture changed from major <100> + minor <111> fiber texture to the <111>-<112> textures as annealing time increased, and the microstructural analysis showed that abnormally grown grains emerged at the surface region of wire and grew along the axial direction more rapidly than along the radial direction. The results implies that the primary recrystallization texture is the major <100> + minor <111> fiber texture regardless annealing temperature, whereas the <111>-<112> textures are due to abnormal grain growth. The results together with orientation distributions along the radial direction of the annealed specimens are discussed based on the strain energy release maximization model for recrystallization textures and a grain growth model.
25.
Park, H. and D. N. Lee (2001). "Deformation and Annealing Textures of Drawn Al-Mg-Si Alloy Tubes." Journal of Materials Processing Technology 113: 551-555.
26.
Park, H. and D. N. Lee (2002). Effects of Shear Strain and Drawing Pass on the Texture Development in Copper Wire. ICOTOM 13, Seoul, Korea, Trans
Tech Publications Inc.
The deformation texture of an electrolytic copper rod drawn to 90% in area reduction was measured by X-ray diffraction and EBSD. The texture in drawn wire changed from a strong <111>+ weak <100> texture in the center region to weak {112}<111> and {110}<001> circular textures in the middle and surface regions. The developments of local textures were discussed by the simulation based on the theory of crystal rotation and finite element method.
27.
Park, H. and D. N. Lee (2003). "The evolution of annealing textures in 90 pct drawn copper wire." Metallurgical and Materials Transactions A 34-A(3): 531-541A.
An electrolytic copper rod was drawn in 24 passes to a 90 pct reduction in area and subsequently annealed under various conditions. The global texture of the drawn wire, as measured by X-ray methods, showed a fiber texture approximated by a strong <111> and a weak <100> component. However, its microtexture, as measured by electron backscattered diffraction (EBSD), indicated that the major <111> + minor <100> duplex fiber texture was dominant only in the center region, while a relatively diffuse texture developed with a somewhat higher density of orientations having a <11w>//wire axis in the middle and surface regions. The inhomogeneous texture in the as-deformed wire gave rise to an inhomogeneous microstructure and texture after annealing. When annealed at 300 deg C or 600 deg C for 3 hours, the wire developed a duplex fiber texture consisting of major <100> + minor <111> components in the center region, a strong <100> fiber texture in the middle region, and a weak texture consisting of <111> and <100> components with the <111> component being slightly stronger in the surface region. When the drawn wire was annealed at the high temperature of 700 deg C, the texture at short annealing times was similar to that of the wire annealed at the lower temperatures of 300 deg C and 600 deg C for 3 hours, but prolonged annealing gave rise to a texture ranging from the <111> to <112> components due to abnormal grain-growth that started in the surface region. The recrystallization texture consisting of the major <100> + minor <111> components was explained by the strain-energy-release maximization (SERM) model, in which the recrystallization texture is determined such that the absolute maximum principal stress direction due to dislocations in the deformed state is along the minimum elastic-modulus direction in recrystallized grains. On the other hand, the abnormal grain-growth texture was attributed to grain-boundary mobility differences between differently oriented grain.
28.
Park, H. and H. M. Chan (2002). "A novel process for the generation of pristine sapphire surfaces." Thin Solid Films 422(1-2).
Sapphire is widely used as a substrate material for blue light emitting diode and laser diode devices, as well as for visible/infrared window and radome applications. The ensuing component performance is highly dependent on the quality of the surface finish, and degree of subsurface damage. A novel process has been developed which has the potential to replace the final stage chemical and mechanical polishing steps currently necessary to achieve the requisite surface finish. The process entails deposition of a thin film of Al on the (0 0 0 1) sapphire substrate, followed by an oxidation anneal. The final step is grain growth of the underlying substrate, which leads to complete single crystal conversion. The influence of heat treatment conditions on the final surface finish was investigated. Microstructural and topographical development of the surface layer was studied using scanning electron microscopy, orientation image microscopy, and atomic force microscopy.
29.
Park, H., D.-Y. Kim, et al. (2004). "Microstructural evidence of abnormal grain growth by solid-state wetting in Fe-3%Si steel." Journal
of Applied Physics 95(10): 5515-5521.
In this investigation, the mechanism of abnormal grain growth in Fe-3%Si steel was based on the microstructure evolution at the growth front of grains undergoing the abnormal growth. The most striking feature in the growth of abnormal grains was the penetration along the grain boundary of neighboring grains. This is energetically possible if the energy of the penetrated grain boundary is higher than the sum of the energy of two other grain boundaries shared by the penetrating abnormal grain. Along the growth front of an investigated abnormally growing grain, 15 out of 1381 triple junctions showed the clear microstructural evidence of the grain boundary penetration by the abnormal grain. Misorientation measurements of 34 penetrated grain boundaries using electron backscattered diffraction showed that not a single boundary has a low angle, implying that the penetrated grain boundaries have the high energy. These results are best explained by the abnormal grain growth with solid-state wetting.
30.
Park, H., H. M. Chan, et al. (2005). "Patterning of sapphire substrates via a solid state conversion process." Journal of Materials Research 20(2): 417-423.
Nanopatterned sapphire substrates offer the potential for improved performance of devices based on III-V nitrides, e.g., light-emitting diodes and laser diodes. Due to the chemical stability and hardness of sapphire, however, surface patterning is a time-consuming and expensive process. Therefore, a novel method was utilized, whereby a surface coating of Al was deposited on a sapphire substrate and patterned into an array of square mesas using e-beam lithography. The lateral dimensions of each mesa were approximately 400 x 400 nm, and the average height was approximately 100 nm. The metallic film was subsequently subjected to an oxidation treatment at 450° C for 24 h (a heat treatment which had previously been shown to minimize hillock formation). For the second heat treatment, which is necessary to induce migration of the sapphire interface and hence achieve solid state conversion, a range of temperatures (800 - 1350 ° C) was explored. Results showed that for a heat treatment time of 1 h, pattern retention was achieved for annealing temperatures less than or equal to 1250° C. Successful epitaxial conversion of the patterned mesas to sapphire was confirmed using electron backscatter diffraction.
31.
Park, J. K., S. Y. Ok, et al. (2005). Austenite-to-Ferrite Transformation of Plain Low Carbon Steel During Deformation within a (γ + α) Two-Phase Field. Solid to Solid Phase Transformations in Inorganic Materials 2005, Phoenix, Arizona, USA, TMS.
Dynamic transformation of plain low carbon steel occurred by massive transformation at temperature below T0 within 2-phase field at strain rates slower than about 0.1s-1. The critical strain for dynamic transformation was characteristically low as compared to that for strain induced transformation, which occurred at above T0 within 2-phase field. The transformation rate by dynamic massive transformation was controlled by imposed strain rate. Grain refinement of massive ferrite occurred through continuous dynamic recrystallization of massive ferrites.
32.
Park, J. Y. and J. A. Szpunar (2002). Influence of the Primary Recrystallization Texture on Abnormal Grain Growth of Goss Grains in Grain Oriented Electrical Steels. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Goss texture development in high permeability grain oriented electrical steel (HGO) and conventional grain oriented electrical steel (CGO) was compared through the analysis of the primary recrystallization texture. Texture and microstructure of the specimens were analyzed using Orientation Distribution Function (ODF) calculated from X-ray diffraction, optical microscopy and OIM (Orientation Imaging Microscopy). The?-fiber texture component was transformed when grain oriented electrical steel was annealed primarily. However, the dominant texture along the?-fiber was developed differently in CGO and HGO, respectively. The {111}<110> texture was a dominant component in CGO, but {111}<112> was dominant in HGO. The influence of the primary recrystallization texture on abnormal grain growth of Goss grains in grain oriented electrical steels was discussed based on the high-energy grain boundary theory.
33.
Park, J. Y., J. T. Choi, et al. (2002). Microstructure and Texture Analysis in Twin-Roll Strp Cast Fe-36wt%Ni Alloy. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
Fe-36wt%Ni alloy sheet was produced using a vertical type twin roll strip casting process followed by cold rolling and annealing. The microstructure and texture through the thickness direction of as-cast strip, in cold rolled and annealed specimens were studied using Orientation Distribution Function (ODF) calculated from X-ray diffraction, optical microscopy, and OIM (Orientation Imaging Microscopy). The columnar dendrites zone had been tilted by an angle of 25° to 30° from the strip normal direction. In the dendrite zone, {100} fiber texture evolved through the thickness direction. In the center layer, minor copper type texture component was formed. During the strip casting, plane strain compression in the center layer could be the reason for the evolution of the copper component. During cold rolling, ß-fiber texture, which is a typical deformation texture in FCC metals, was developed, but weak cube component was evolved simultaneously. Strong {100}<001>, cube texture, was most likely formed during the final annealing of the cold rolled strip.
34.
Park, J. Y., K. H. Oh, et al. (1999). Microstructure and crystallographic texture of strip-cast 4.3%Si steel sheet. Twelfth International Conference on Textures of Materials (ICOTOM 12), McGill University, Montreal, Canada, NRC Research Press.
35.
Park, J. Y., K. S. Han, et al. (2002). "Influence of primary annealing condition on texture development in grain oriented electrical steels." Acta Materialia 50: 1825-1834.
The development of texture and microstructure in two kinds of conventional grain oriented electrical steels, which were annealed at different primary annealing temperature, were investigated. The specimens were analyzed using Orientation Distribution Function (ODF), optical microscopy and OIM (Orientation Imaging Microscopy). The size distributions of AlN precipitates, which were used as grain growth inhibitors, were investigated using transmission electron microscope (TEM) and an image analyzer. The influence of primary annealing conditions on the secondary recrystallization in conventional grain oriented electrical steels was discussed based on information on precipitate distributions and the kinetics of abnormal grain growth of Goss grains. When the high energy boundary theory and the driving force for the Goss grain growth are considered, it is possible to explain the reason for significant improvement of the final texture and magnetic properties in the specimen that was recovered before the final annealing compared to the specimen that was recrystallized.
36.
Park, J., J. A. Szpunar, et al. (2002). Effect of Temper Rolling Reduction and Annealing Time on Texture Formation during Final Annealing in Electrical Steels. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The magnetic properties of semi-processed nonoriented electrical steels are significantly improved by strain induced boundary migration (SIBM) during final annealing. In order to investigate the possibility of texture control, temper rolling reduction was changed in the range of 2% to 8 % and annealing time in the range of 10 minutes to 180 minutes. Furthermore, based on observed experimental data, a mechanism of grain growth during SIBM is suggested. Temper rolling reduction plays an important role in deciding the texture developed after SIBM. In the specimen temper rolled by 2%, relatively strong {111}<112> texture develops, whereas in the specimens temper rolled by 4% through 8%, strong Goss texture develops as a result of SIBM during final annealing. The latter case can be explained by the fact that the Goss grains have the lowest stored energy in temper rolled state, which is confirmed by average image quality value in EBSD measurements. However, for the Goss grains to grow preferentially, stored energy difference between two neighboring grains may have to be higher than a certain critical value. The grain growth by means of SIBM happens earlier in the specimen temper rolled by higher reduction.
37.
Park, J., J. A. Szpunar, et al. (2002). Effect of Initial Grain Size Prior to Cold Rolling on Annealing Texture in Non-Oriented Electrical Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The magnetic properties of nonoriented electrical steels are influenced by grain size and texture. The problems related to grain size control have been investigated extensively, while texture control has received much less attention. The initial grain size, which is considered an important factor in the texture control, was changed by annealing the hot band at different temperatures. The specimens having different initial grain sizes had significantly different textures in the cold rolled state. As a result, different textures were also observed in partially recrystallized specimens and those where recrystallization was completed and grain coarsening has taken place. During the recrystallization stage, new grains formed in the coarse-grained specimen had stronger Goss but weaker y-fibre texture than those in the fine-grained specimen. During the grain coarsening after complete recrystallization, the coarse-grained specimen still had weaker y-fibre texture than the fine-grained specimen, but there was no significant difference in the Goss texture component. However, after grain coarsening at 950°C, the Cube texture component was stronger in the coarse-grained specimen thatn in the fine-grained specimen.
38.
Park, J.-T., J. A. Szpunar, et al. (2005). Texture Development during Final Annealing in Nonoriented Electrical Steels. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
Nonoriented electrical steels have been widely used as core materials in motors and generators. For these applications low core loss and high permeability are required. The magnetic properties of these steels depend on the grain size and crystallographic texture of the annealed final products. The problems related to grain size control have been extensively investigated, while texture control has received much less attention. The technologies used to control the grain size in nonoriented electrical steels have approached to their limits. However, there is still some possibility for improvement of the magnetic properties through texture control. In order to explore this possibility, the evolution of recrystallization texture for nonoriented electrical steels with 2% Si was systematically studied. Texture change during grain growth was additionally analyzed. The formation of recrystallization texture is explained by oriented nucleation. This is supported by the fact that the area fraction of nuclei or recrystallized grains with specific orientation to all new grains remains almost constant during the progress of recrystallization. Most nuclei have a high misorientation angle of 25~55° with the surrounding deformed matrices. During the progress of grain growth, Goss and {111}<112> components are weakened and the random texture is strengthened. The grains of the Goss and {111}<112> orientations have smaller grain size than those of random orientation.
39.
Park, K. H., C. Y. Kim, et al. (1995). "Microstructures and Interdiffusions of pt/Ti Electrodes with Respect to Annealing in the Oxygen Ambient." Journal of Materials Research 10(7): 1790-1794.
40.
Park, K. K., J.-H. Cho, et al. (2003). "Texture evolution during deep drawing of Mo sheet." Key Engineering Materials: 567-572.
Texture evolution of the deep drawing of molybdenum sheet was investigated with EBSD (Electron Back Scattered Diffraction), X-ray diffraction techniques and orientation distribution function (ODF) analysis. The texture during deep drawing is hardly changed due to the strong of initial texture. Specimens symmetry of 45 deg from rolling direction have monoclinic symmetry during deep drawing process. EBSD can be used for the quantitative determination of macroscopic texture as like X-ray diffraction techniques if a sufficient number of grains are measured. Grain sizes show the similar values during deep drawing process but their values along 45 deg direction from rolling direction at flange and wall are tend to increase. It is associated with the 45 deg earing of deep drawing processing. The correlation function values were -0.58 for RD flange and -0.36 for RD wall and suggest that high Taylor factor regions have low pattern quality and low Taylor factor regions have high pattern quality.
41.
Park, K. K., S. T. Oh, et al. (2002). In Situ Deformation Behavior of Retained Austenite in TRIP Steel. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
To investigate the stability of retained Austenite under plastic deformation and the change of volume fractions of each phase, the microstructural characterization such as shape and orientation of retained austenite as uniaxial tension tests, including HR-EBSD observations, for TRIP steel made by POSCO have been carried out. In-situ and ex-situ mechanical test with EBSD measurement revealed the deformation sequence of multi phase steels and predicted the stability of retained austenite with its size. The granular type (>1µm) of retained austenite transformed faster than that of lath or film type (<1µm), which is well known from TEM measurement.
42.
Park, N.-J. and D. P. Field (2006). "Predicting thickness dependent twin boundary formation in sputtered Cu films." Scripta Materialia 54(6): 999-1003.
Triple junctions involving twin boundaries in Cu interconnects of integrated circuits have been shown to be potentially detrimental to the manufacturability of the circuit. Microstructures of annealed Cu films are dependent on film thickness and deposition parameters. This work describes texture and twin boundary development in sputtered and annealed Cu films.
43.
Park, N.-J., D. P. Field, et al. (2005). "Effect of Film Thickness on the Evolution of Annealing Texture in Sputtered Copper Films." Journal of Electronic Materials 34(12): 1500-1508.
Microstructural evolution during elevated temperature annealing of sputter deposited copper (Cu) films was investigated by electron backscatter diffraction (EBSD). Analysis of films was performed both in situ using a heating stage, and by ex-situ observation of microstructural evolution. It was noted that not only is the Cu film texture and grain size a function of film thickness, but also that the fraction of twin boundaries present in the material is strongly dependent upon film thickness. This is explained by means of a simple model that considers the energy of the system. Surface and interface energies, as well as grain boundary energies for random high angle boundaries and for twin boundaries (both coherent and incoherent planes) are used in the determination. The model was shown to accurately predict the twin boundary size in self-annealed films. This type of analysis also results in a texture map similar to that presented by Thompson, but incorporates the development and effect of twin boundaries, so that additional texture components (in addition to 111 and 100 fibers) are included.
44.
Park, S. H., K. Y. Kim, et al. (2000). Effect of Initial Orientation and Austenitic Phase on the Formation of Deformation Band and Recrystallization Behavior in Hot Rolled Ferritic Stainless Steels. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
The hot rolling behaviour of solidified columnar crystals in ferritic stainless steels has been investigated in order to clarify the effect of initial orientation and austenitic phase on the evolution of deformed microstructure and nucleation. The columnar crystal specimens prepared from continuous casting slab were hot rolled and annealed. The rolling and recrystallization textures were examined by orientation distribution function (ODF), The crystal rotation of each columnar grain and local disorientation near the austenitic phase were examined by electron back-scattered diffraction (EBSD). The microstructure and texture evolution afler hot rolling and annealing depends more strongly on the initial orientation rather than the existence of austenitic phase. These features are discussed relevant with the formation of inhomogeneous microstructure and nucleation at deformation bands.
45.
Park, S. H., K. Y. Kim, et al. (2002). Evolution of Microstructure and Texture Associated with Ridging in Ferritic Stainless Steels. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The evolution of microstructure and texture in two ferritic stainless steels was investigated in order to identify the existence of grain colonies associated with ridging and their origin. Special attentions were placed on examining how the columnar crystals with an initial [001]//ND orientation in continuously-cast slabs can affect the formation of the grain colonies or band structures in the cold-rolled sheet specimens. The rolling and recrystallization textures at each process stage were examined by the orientation distribution function (ODF). Microtexture measurements using an electron back-scattered diffraction (EBSD) technique were carried out on the ND, RD, and TD sections respectively. The existence of grain colonies having both {001}<110> and {112}<110> orientations at the central region of the sheets was clearly identified. These orientations were caused by both the crystal rotation toward the a-fibre texture, which is stable orientation during rolling and the suppressed recrystallization. The relation between the presence of grain colonies and ridging phenomena was discussed.
46.
Park, S.-H., H.-G. Kang, et al. (2005). Effect of the Rolling Draughts on the Evolution of Textures and Microstructures in 17.5 Cr-1.1 Mo Ferritic Stainless Steel Sheet. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
In order to investigate the effect of the reduction degree per rolling pass on the evolution of recrystallization textures and microstructures, the hot band of 17.5 Cr-1.1 Mo ferritic stainless steel sheets were cold rolled with lubrication according to two processing routes, by which different reduction degrees per pass were introduced. Rolling with a large number of passes led to the formation of fairly homogeneous rolling textures at all through-thickness positions. In contrast, cold rolling with large draughts resulted in pronounced texture gradients along the thickness direction. After recrystallization annealing, the texture maximum was obtained at {334}<483> in all samples regardless of the rolling routes and thickness layers. During subsequent annealing, recrystallization was observed to be faster in those grains with {111}<uvw> orientations, while it was retarded in grains having orientations close to {001}<110>.
47.
Park, S.-H., Y. S. Sato, et al. (2003). "Basal Plane Texture and Flow Pattern in Friction Stir Weld of a Magnesium Alloy." Metallurgical and Materials Transactions A 34A(4): 987-994.
The microtextures in a friction-stir-welded magnesium (Mg) alloy, AZ61, with a nugget-shaped stir zone were analyzed by orientation imaging microscopy (OIM). The base material had a (0002) <uvi0> texture ([0002] parallel to the sheet plane, <uvi0> parallel to the welding direction). Friction stir welding produced texture components different from those of the base material in the stir zone. Except for the upper surface of the plate, most of the stir zone had a texture with a strong tendency for the (0002) basal plane to align with the surface of the hard pin of the welding tool. Formation of this texture component was attributable to shear deformation arising from the rotation of the hard pin. The (0002) planes tended to align with an ellipsoidal surface in the nugget-shaped stir zone. The present study suggests that the nugget shape, which is a characteristic feature of the stir zone, is strongly related to formation of the ellipsoidal surface described by the (0002) basal plane.
48.
Park, Y. B., D. N. Lee, et al. (1998). "The Evolution of Recrystallization Textures in Body Centred Cubic Metals." Acta Materialia 46(10): 3371-3379.
A model of the evolution of recrystallization textures for b.c.c. metals was suggested based on the ODF and EBSD analysis of the texture change during annealing of cold rolled steel. The model is composed of two principles: first, the maximum principal stress direction in the deformed grain becomes the minimum Young's modulus direction in the recrystallized grain; second, a {110} plane, parallel to the maximum principal stress direction (hence, minimum Young's modulus direction), is taken for variant selection. The current model is successfully applied to describe the evolution of recrystallization textures in various b.c.c. transition metals such as tantalum, molybdenum and tungsten.
49.
Park, Y. B., J. Park, et al. (2000). Development of Textures in Nanocrystalline Ni-20wt-%Fe Alloy. Thermec 2000, Las Vegas, Nevada, USA, Elsevier Science Ltd.
The present study has been carried out to investigate the development of textures and microstructures during the annealing of a nanocrystalline Ni-20wt-%Fe alloy fabricated by electrodeposition. The as-prepared specimen with a grain size of 12 nm revealed a strong {100} and a weak {111} fibre-type textures. Grain growth in the material occurred on annealing beyond 370°C and resulted in the texture change that the {111} fibre strongly developed at the expense of the {100} fibre. It was observed using orientation imaging microscopy (OIM) that the {111} grains are much coarser than other oriented grains in the early stages of grain growth. The relationship between the texture evolution and the microstructural change that take place during annealing is interpreted and discussed in terms of the orientation dependency of grain growth
50.
Park, Y. B., J. Park, et al. (2002). Texture Evolution during the Annealing of Nanocrystalline Permalloy. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The texture evolution that takes place suring annealing was investigated in a nanocrystalline Fe-78wt%Ni permalloy fabricated by using an electrodeposition method. The as-deposited texture was characterized by a strong <100>//ND fibre and a weak <111>//ND fibre. Grain growth occurred during annealing beyond 340°C and resulted in the texture change that the <111>//ND fibre strongly developed at the expense of the <100>//ND fibre. It was observed using orientation imaging microscopy that the <111>//ND oriented grains abnormally grew in the early stages of grain growth. The relationship between the texture evolution and the microstructural change during annealing is interpreted and discussed in terms of the orientation dependency of grain growth.
51.
Parteder, E., T. Siegmund, et al. (1995). "Numerical simulation of the plastic behavior of polysynthetically twinned Ti-Al crystals." Materials Science and Engineering A 192/193: 149-154.
A micromechanical model describes the deformation behavior of Ti-Al intermetallics with a gamma -TiAl- alpha2-Ti3Al lamellar structure. The tension-compression load orientation angle theta varies with respect to the lamellae from 0 degrees <or= theta <or=90 degrees. Extended crystal plasticity (ECP) for the gamma phase considering the significantly different free paths for dislocations on the various slip systems predicts both the yield stress and the hardening behavior in good agreement with experiment. Neither Mises flow plasticity nor standard crystal plasticity reproduce these results satisfactorily. Near theta =90 degrees, application of the ECP model for the gamma phase also underestimates the yield stress, mainly owing to the representation of the alpha2 phase by a purely elastic material. Some improvements are suggested by introducing an ECP description also for the alpha2 phase, distinguishing between pyramidal and prism slip systems. (24 References).
52.
Paul, H. (2004). "Study of the microtexture of recrystallized aluminium." Microchimica Acta 145(1): 153-158.
The nucleation of recrystallized grains in deformed, high-purity aluminium were examined in relation to the microstructural heterogeneities in the form of shear bands (SBs) and transition bands (TBs). The experiments were carried out on single crystals deformed in channel-die compression at 77 K to true strains within the range of 1-1.5. The substructures were identified by means of a combination of transmission (TEM) and scanning (SEM) electron microscopes. Local texture measurements in particular places of samples were mostly investigated by means of TEM and convergent beam electron diffraction (CBED), with on-line diffraction pattern analysis. The coarser analyses were performed by SEM and electron back scattered diffraction (EBSD). The C{112} (111) and the S{531} (123) oriented single crystals are stable in the global sense and form clearly defined SBs. The H{110} (110), and the left dbl quote shear right dbl quote {100} (011) orientations are very unstable and tend to form TBs. The nuclei of new grains formed along the band are misoriented by small alpha "(111) or (112)" with respect to the orientations identified within the neighbouring banded material. The author attempts to explain, from the crystallographic point of view, the processes operating within high stacking fault energy metals at the very early stages of recrystallization.
53.
Paul, H. and J. H. Driver (2004). Recrystallization Nucleation in Some Channel Die Deformed, High Symmetry Aluminium Bicrystals. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
54.
Paul, H. and J. H. Driver (2005). "Deformation Behaviour of Channel-Die Compressed Al Bicrystals with (IOW < 001 > /{110} < 011 > Orientation." Archives of Metallurgy and Materials 50(1): 209-218.
The formation of band-like heterogeneities in deformed grains and the evolution of their microtexture components during large plastic deformations is examined in Al bicrystals. The study has focussed on bands developed by plane strain compression in {100} < 001 > /(110} < 011 > (soft/hard)-oriented high purity aluminium bicrystals with the boundary plane situated parallel to the compression plane. The character of the bands was determined by systematic local orientation measurements using EBSD in SEM-FEG scanning electron microscope and also by transmission electron microscopy (TEMICBED) at specific locations. The bicrystal deformation analysis shows that the microtexture evolution in each crystallite is quite different. Very strong deformation banding in the 'cube' grain is initiated by strain incompatibilities and giving initial rotations about transveres direction. At very high strains where the flow is inhomogeneous, clearly defined rotations about a < 112 > axis are observed, suggesting localized single (111} < 110 > slip in areas of the band. The `hard' {110} < 011 > -oriented grains are more stable under plane strain conditions except for the zone near the grain boundary where strong micro-textural/structural disturbances are observed.
55.
Paul, H., J. H. Driver, et al. (2002). "Shear banding and recrystallization nucleation in a Cu–2%Al alloy single crystal." Acta Materialia 50: 815-830.
High-purity Cu–2%Al single crystals with initial C{112}<111> orientation have been deformed by channel-die compression at 77 and 293 K to develop fine shear bands in a twin-matrix (T-M) substructure. The microstructural and microtextural changes during deformation and the early stages of recrystallization have been studied in detail by TEM/CBED and SEM/EBSD. Local orientations measurements indicate that the scattering of the original T-M orientations within shear bands towards two, twin-related positions is due to the localised lattice rotation around the TD || <011> axis. The starting points for the occurrence of new, recrystallized grains are the {110}<100> and {114}<221> components of the as-deformed microtexture inside the shear bands. As recovery and recrystallization proceed, the orientations of the primary nuclei systematically evolve to adopt simple boundary misorientation relations of ~30°<111> type with respect to one of the two components of the deformed matrix. The results of the present study clarify the respective roles of all three basic mechanisms, i.e. oriented nucleation, growth (defined here as ~30°<111>) and recrystallization twinning which are involved in the initial stages of recrystallization texture development in this low stacking fault energy alloy.
56.
Paul, H., J. H. Driver, et al. (2002). "Crystallographic aspects of the early stages of recrystallisation in brass-type shear bands." Acta Materialia 50(17): 4339-4355.
The orientations of recrystallisation nuclei and their adjacent, as-deformed regions have been characterised in deformed single crystals of different metals (Cu, Ag and Cu–2%Al) in which twinning and/or shear banding occur. The {112}<111> oriented crystals of these metals have been plane strain compressed to different strains then lightly annealed and the crystallographic aspects of the recrystallisation process along shear bands (SB) examined by TEM/CBED and SEM/EBSD. The results clearly show the existence of a well-defined crystallographic relation between the local deformation substructure and the first recrystallised areas of uniform orientation. The first-formed nuclei always exhibit near 30o<111> type misorientations, in the direction of highest growth with respect to one of the two main groups of the deformation texture components. The <111> rotation axis can be correlated with one of the slip plane normals of high activity within the SB. As recrystallisation proceeds, recrystallisation twinning develops strongly and facilitates rapid growth; the first and higher generations of twins then tend to obscure the initial primary crystallographic relation between the SB and recrystallisation nuclei.
57.
Paul, H., J. H. Driver, et al. (2003). "Shear band microtexture formation in twinned face centred cubic single crystals." Materials Science and Engineering A 359(1-2): 178-191.
The formation of brass-type shear bands (SB) in twinned microstructures of medium and low stacking fault energy (SFE) metal single crystals (copper, copper-2 wt.% aluminium and silver), with initial orientation {112}<111> has been investigated after channel-die deformation at 77 and 293 K. The microstructures and local orientations were characterised over a wide range of scales by convergent beam electron diffraction in a transmission electron microscope, electron backscattered diffraction in a scanning electron microscope and optical metallography. For all metals it is shown that slip initially causes a general rotation to D(4411) 11118, which is then followed by partial twinning to the D exp T (26 26 5) 5552 orientation. Subsequent shear banding of the unstable, layered, twin structure is responsible for the development of the strong Goss {110}<100> orientation within the bands. A minor group of components is observed near {114}<221>, arising from the near primary matrix orientation. The intensity of mechanical twinning, and therefore, the relative amounts of primary matrix and twinned material, influences the SB internal microstructure. Alloys with low SFE such as Cu-2 wt.% Al deformed at 77 K twin almost completely whereas Cu at 77 K and Ag at 293 K retain significant quantities of (re-oriented) matrix and hence a relatively strong secondary microtexture component within the brass-type bands.
58.
Paul, H., J. H. Driver, et al. (2004). The Formation of New Orientations during Recrystallization of Silver Single Crystals with {112}<111> Initial Orientation. Second Joint International Conference on Recrystallization and Grain Growth, ReX & GG2, SF2M, Annecy, France, Trans Tech Publications Ltd.
59.
Paul, H., J. H. Driver, et al. (2005). Mechanisms of New Orientaion Formation During Recrystallization of Cold Deformed Aluminum Bicrystals. Textures of Materials - ICOTOM 14, Leuven, Belgium, Trans Tech Publications.
The crystallography of recrystallization nucleation has been investigated in channel-die deformed pure aluminium bicrystals with {100}<011>/{110}<001> and {100}<001>/ {110}<001> orientations. The new grain orientations and misorientations were followed by systematic local orientation measurements using SEM and semi-automatic measurements in a TEM. In particular, orientation mapping combined with in-situ sample heating was used to investigate the formation and growth of new grains and their crystallographic orientation changes at very early stages of recrystallization. Grain boundary migration and ‘consumption’ of the as-deformed areas was always favoured along directions parallel to the traces of the {111} slip planes that had been most active during deformation. The orientations of the first formed nuclei were misoriented with respect to the orientations identified within the neighbouring deformed areas by α(<111>, <112>, or <100>) relations.
60.
Paul, H., Z. Jasienski, et al. (2002). Early Stages of the Recrystallization Texture Formation in {112}<111> - Oriented Silver Single Crystals. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The microtextural changes occurring during recrystallization in high purity silver single crystals with C(112)[111] initial orientation, deformed by channel die compression, have been studied in detail. The obtained results indicate the great importance of the simple relation of 25-35° <111> type, which is observed most frequently at the early stages of the recrystallization process, between isolated nuclei of uniform orientation and one from the as-deformed components identified within shear bands. Any twin relations between the deformed and the recrystallized phase were not observed. Accordingly, the recrystallization twinning might be regarded only as a secondary mechanism, which is responsible for the growth of the recrystallized phase. The authors try, from the crystallographic point of view, to systematize the validity of the processes operating at the very early stages of the primary recrystallization of fcc metals, and to show thee way in which the rotation axes were chosen.
61.
Pech-Canul, M. I., M. Rodriguez-Reyes, et al. (2006). "Limiting the development of Al4C3to prevent degradation of Al/SiCp composites processed by pressureless infiltration." Composites Science and Technology 66(7-8): 1056-1062.
The presence of Al4C3 in Al/SiC composites may activate degradation of the material by its interaction with water; even moisture may cause its environmental degradation. It has been demonstrated that incorporation of 6vol% SiO2 powders into SiCp preforms before processing by pressureless infiltration prevents formation of Al4C3. Analysis by electron back-scattered diffraction confirms that regardless of its crystal structure (α-quartz or α -cristobalite), SiO2 completely reacts to form MgAl2O4. The metal/composite interface microstructure condition of the specimens processed under the most severe conditions (1100 degrees C for 60min), four months later confirms the effectiveness of the SiO2 powders.
62.
Pedzich, Z. and M. Faryna (2004). Fracture and crystallographic phase correlation in alumina particulate composites. 2nd International Conference on Fractography of Advanced Ceramics, Stara Lesna, Slovakia, Trans Tech Publications.
The paper deals with the results of mechanical properties and microstructure investigations performed in two composite systems: Al2O3/WC and Al2O3/W. The fracture toughness measurements were made for materials characteristics. Microstructure of composites was thoroughly investigated using transmission and scanning electron microscopy. Selected area electron diffractions (SAEDs) as well as electron backscatter diffractions (EBSDs) were applied to establish crystallographic relationships between neighboring grains of different phases both in a local and global scale. Examples of orientation maps and stereographic projections for different crystallographic directions as well as orientation relationships between different phases (alumina and reinforcing inclusions) were shown and described.
63.
Pei, Y. T. and J. T. M. De Hosson (2001). "Five-fold branched Si particles in laser clad AlSi functionally graded materials." Acta Materialia 49(4): 561-571.
Many five-fold branched Si particles (Sip) were observed in Al–40 wt% Si functionally graded materials produced by a single-step laser cladding process on cast Al-alloy substrate. In this paper the five-fold twinning and growth features of Sip are scrutinized with orientation imaging microscopy and electron microscopic examination. It is a more in depth study of formation of the Si particles in functionally graded materials as published in our previous paper [Pei, Y. T. and De Hosson, J. Th. M., Acta mater., 2000, 48, 2617]. These Si particles have grown from twinned decahedron nuclei consisting of five tetrahedrons that share a common 110 axis. The twin plane re-entrant edge (TPRE) mechanism explains both the branch growth in the radial direction and the elongation of Sip along their common 110 axis. Subsequent twinning within the twinned tetrahedrons provides additional re-entrant grooves on their top faces, which are important for the rapid elongation and consequently for the continuous growth of the branched particle. The 7.5° mismatch that arises by putting together five tetrahedrons around a common 110 axis is accommodated by small-angle grain boundaries (SAGBs). The SAGBs may disturb the progress of growth steps, which causes the particles to branch. The most remarkable facts of the study are that the five-fold branched silicon particles are much bigger (2540 μm) than the nanometer sizes previously reported in the literature and the 7.5° mismatch is accommodated mainly by multiple SAGBs. The examples of a single SAGB reported before are just a special case of the SAGB mechanism.
64.
Pekarčı́ková, M., S. Menzel, et al. (2005). "Electron back scattered diffraction study of acoustomigration damage in Al/Ti metallization for SAW devices." Microelectronic Engineering 82(3-4): 650-654.
The correlation between the microstructure of a 340 nm thick Al metallizations deposited on a thin Ti adhesive layer and damage due to acoustomigration was investigated. For this reason, the {1 1 1} textured metallization was acoustically loaded by gradually increasing rf power up to 3.6 W. The hillock and void formation during load experiments was mostly detected at such grain boundary triple junctions, which consist of two grain boundaries with misorientation angles <30° and one grain boundary with a misorientation angle >30°. The results were achieved by means of scanning electron microscopy, electron back scattered diffraction, and focused ion beam technique.
65.
Penelle, R. and T. Baudin (1993). "Microtexture Characterization by EBSP in Iron and Titanium Alloys." Textures and Microstructures 20(1-4): 165-78.
66.
Penelle, R. and T. Baudin (2006). "Multiscale approach to texture-microstructure coupling." Materials Science Forum 509: 1-10.
Materials exhibit microstructures and textures that influence their use and properties. X-ray and neutron diffraction allow characterization of the bulk texture, whereas electron backscattered diffraction (EBSD) permits determination of the local texture. In many cases transmission electron microscopy (TEM) remains necessary to characterize the substructure and the local texture for highly deformed materials. Depending on the scale considered, all these complementary techniques permit the coupling of texture and microstructure so that it becomes possible to control microstructure and its evolution during a processing route. Some examples in titanium aluminides, (α + β) titanium alloys and an Fe-Ni alloy will illustrate this challenge.
67.
Penelle, R., T. Baudin, et al. (1990). Characterization of Recrystallization Textures in Fe-3%Si Sheets by EBSP: Comparison with X-ray Diffraction. Ninth International Conference on Textures of Materials (ICOTOM 9), Avignon, France, Gordon and Breach Science Publishers.
68.
Penelle, R., T. Baudin, et al. (2002). Formation and Control Texture in Fe-Ni Alloys. ICOTOM 13, Seoul, Korea, Trans Tech Publications Inc.
The present paper is a synthesis of several works performed in the laboratory on mechanisms of the cube texture formation in the Fe-36%Ni alloys which have been studied at a local scale by TEM and EBSD and at a global scale by X-ray and neutron diffraction at the Laboratoire Léon Brillouin (CEA-CNRS) in Saclay. A weak cube component exists after hot rolling, it is quite stable during cold rolling, whereas the copper, aluminum and brass components strengthened with deformation, especially for high reduction (95%). TEM observations of the cold rolled microstructure have shown that the cube bands are made up of well formed sub-grains while th erest of the deformed matrix is composed of lamellar bands containing a high dislocation density. After a short time annealing of 95% cold rolled sheets, the main mechanism of cube sub-grains growth occurs by direct bulging or prior grain boundaries between the cube bands and the matrix into the matrix. Cube sub-grains can also grow, firstly within the cube band through the orientation gradient along the transverse direction, then into the deformed matrix. However, the first mechanism seems more probable because of a favourable difference of deformation stored energy and a high disorientaiton between the growing cube sub-grain and the deformed matrix which provides the driving force to sub-boundary displacement. For 70% cold rolling, all the components develop during annealing, leading to a weak cube texture. Indeed, the stored energy difference is not sufficient to allow the cube grains to grow more rapidly than the others. Moreover, whatever the deformation amounts, multi-twinning occurring during recrystallisation tends to soften the texture as shown experimentally and by simulation.
69.
Peng, Q. J., T. Shoji, et al. (2003). Measurement of compositional profile of ID facets by FEG-AES and its relevance to IDSCC of alloy 182 in a simulated BWR environment. Advances in Fracture and Failure Prevention: Proceedings of the Fifth International Conference on Fracture and Strength of Solids (FEOFS2003): Second International Conference on Physics and Chemistry of Fracture and Failure Prevention (2nd ICPCF), Sendai, Japan.
Environmentally Assisted Cracking (EAC) of weld metal, Alloy 182 is currently great concern in such components as head penetration, control rod drive housing and core shroud supports in nuclear power plants. The microstructure of Alloy 182 is dendritic and the most susceptible crack plane is known to be parallel to the direction of the dendrites. Electron Backscattered Diffraction Patterns (EBSP) analyzed the distribution of the grain boundary character. A compositional profile of the dendritic grain boundary of sensitized Alloy 182 was performed by Field Emission Gun-Auger Electron Spectroscopy (FEG-AES) on the InterDendritic (ID) facets. The dendrites were generated by slow strain rate tests in high vacuum with the tensile stage attached to the AES. For the sample with hydrogen charging, data showed a significant variation of Chromium and Phosphorus concentration on the ID facets. Chromium was depleted down to 2% on some facets and phosphorus was enriched to several % on some facets. The data was evaluated statistically. The FEG-AES technique has an advantage over ATEM that large amounts of data can be obtained. Hundred of data points were obtained by this technique. Stress Corrosion Cracking (SCC) crack growth data obtained in a simulated Boiling Water Reactor (BWR)'s water environment will be discussed along with those compositional profiles on ID facets.
70.
Peng, R. L., M. Oden, et al. (2002). "Intergranular strains and plastic deformation on an austenitic stainless steel." Materials Science and Engineering 334 A(1-2): 215-222.
Intergranular strains due to tensile plastic deformation were investigated in a sheet material of austenitic stainless steel. The objective was to study the development of residual intergranular strains in samples unloaded from the intermediate and large plastic deformation regimes for which few theoretical and experimental studies were available. By using neutron diffraction, residual lattice strain distribution as a function of sample direction was mapped for a number of crystallographic planes. Deformation microstructures were examined by both transmission electron microscopy and the electron back scattering pattern technique. Residual intergranular strains were observed in samples deformed significantly beyond the elastic limit and the strains varied with sample directions as well as the amount of applied plastic strain. In addition, a different tendency of intergranular strain evolution was observed after large plastic deformation, which could be attributed to the change of dominant plastic deformation mode from slip to mechanical twinning. The results are discussed based on the observed deformation microstructure studies.
71.
Pennock, G. M. and M. R. Drury (2005). "Low-angle subgrain misorientations in deformed NaCl." Journal of Microscopy 217: 130-137.
The development of subgrain boundary misorientations with strain in NaCl polycrystals has been investigated. At low strains, a power law relationship exists between strain and average misorientations. The accuracy of this relationship is assessed in terms of material and electron backscattered diffraction (EBSD) processing parameters and is found to hold for a material of constant grain size deformed in compression, providing EBSD mapping and processing conditions were similar. Average misorientations are strongly influenced by grain orientation, suggesting that the misorientation-strain relationship may also be texture dependent in materials with high plastic anisotropy. A slight grain size dependency of the average misorientations was observed.
72.
Pennock, G. M., A. Barnhoorn, et al. (2001). "EBSD of Zeolites." Journal of Materials Science 20: 1099-1101.
73.
Pennock, G. M., M. R. Drury, et al. (2006). "The influence of water on deformation microstructures and textures in synthetic NaCl measured using EBSD." Journal of Structural Geology 28(4): 588-601.
Wet NaCl with >10–15 ppm water shows weakening behaviour compared with dry NaCl containing <5 ppm of water. At strains greater than about 0.1 this weakening is associated with recrystallization but at lower strains there is also considerable weakening that is thought to be associated with pressure solution creep. The development of textures and microstructures in wet, synthetic NaCl polycrystals deformed at elevated temperatures has been investigated using electron backscattered diffraction (EBSD). At very low natural strains (0.07), textures, grain shapes and average misorientations of subgrain boundaries in wet NaCl differ to those found in dry NaCl deformed under similar conditions. In wet NaCl, cube shaped grains, oriented in a hard orientation for slip on the 110[Macro error: Can’t compile this script because of a syntax error.] planes. The possible distribution of these planes types, based on information from the single-surface trace analysis, had a high rank correlation coefficient, 0.925, with previous data from nickel which was based on a two-surface, full boundary planes analysis.
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