Letteratura scientifica selezionata sul tema "Microstructure and crystal texture characterization"
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Articoli di riviste sul tema "Microstructure and crystal texture characterization":
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Zhang, Kai, Knut Marthinsen, Bjørn Holmedal, Jesper Friis, Tanja Pettersen e Antonio Segatori. "Characterization and Modelling of the Microstructure and Texture Evolution in AlMgSi-Extrusions". Materials Science Forum 879 (novembre 2016): 1239–44. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1239.
Abstract (sommario):
The properties and surface appearance of aluminium extrusion are critically dependent on the microstructure and texture of the extruded profiles, and the requirements with respect to these aspects may vary with applications. Moreover it is often a challenge to produce extrusions with a consistent and homogenous grain structure and texture along as well as through the cross section of the profiles. It is thus vital to understand and be able to predict (model) how different microstructures and textures are formed and how they evolve during and after extrusion. In the present work a model framework has been implemented which includes a FEM model to account for the strain, strain rate and temperature along a set of particle paths during extrusion. From these the deformation texture and grain structure are calculated with an appropriate deformation texture model and a sub-structure evolution model, respectively. The sub-structure model have in the present work been coupled to a crystal plasticity model to provide an orientation dependent subgrain size and dislocation density during deformation which provides the driving force for the post-extrusion recovery and possible recrystallization behaviour. The post-extrusion microstructure and texture evolution is calculated with a recovery and recrystallization model, which is accompanied by a recrystallization texture model. The framework and its constituent models and their interplay are presented, and some preliminary results when applying this modelling framework to Al-Mg-Si extrusions are presented and discussed in view of corresponding experimental results.
2
Rahmayeni, Syukri Arief, Yeni Stiadi e Herlin Oktavani. "PEMBUATAN DAN KARAKTERISASI NANOKOMPOSIT MFe2O4 DAN MFe2O4-SiO2 (M = Cu, Ni)". Jurnal Riset Kimia 4, n. 1 (11 febbraio 2015): 55. http://dx.doi.org/10.25077/jrk.v4i1.84.
Abstract (sommario):
Nanocomposites of MFe2O4 and MFe2O4-SiO2 (M= Cu, Ni) were prepared by complexation and complexs polymerization methods using citric acid as complexing agent, tetraethylorthosilicate (TEOS), metal (Cu, Ni) nitrate and iron chloride as precursors. FT-IR spectroscopy was used to analysis the complexation and polymerization process. The decomposition of material was investigated by TG-DTA. Microstructure characterization was carried out by XRD and SEM. Peaks in XRD pattern indicate that the nanocomposites products consist of copper iron oxide (CuFe2O4) and (NiFe2O4) crystals, copper iron oxide crystal distributed in silica (CuFe2O4-SiO2) and nickel iron oxide crystal distributed in silica (NiFe2O4-SiO2). SEM images of CuFe2O4 and NiFe2O4 show that the composites have porous and spherical texture. The surface texture of CuFe2O4-SiO2 composite is triangel like and has porous but NiFe2O4-SiO2 is not regulated texture and has porous. Keywords: MFe2O4, MFe2O4/SiO2, citric acid and complexs polymerization method
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Rauch, Johannes, Frank Kern e Rainer Gadow. "Polarization Light Optical Texture Analysis for the Structural Characterization of CIM Components". Advances in Science and Technology 45 (ottobre 2006): 1690–95. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1690.
Abstract (sommario):
The mechanical properties of ceramic injection molded (CIM) components are largely influenced by microstructural inhomogeneities that result from the interaction of rheological properties of the thermoplastic feedstock with machine parameters and the design of mold and injection gate. These inhomogeneities (e. g. texture, turbulences, joints, and density gradients) can form weak spots in the material or lead to anisotropy of the material properties. Additionally, they can influence the local sinter shrinkage behavior and thereby lead to the formation of residual stresses in the component. For this reason, it is of great importance to analyze these inhomogeneities in order to improve CIM processes and CIM components. A method has been developed for the investigation of preferred crystal orientation and microstructural defects, applying polarization microscopy of ceramic thin sections and colorimetry. Polarization microscopy is used in order to visualize the crystal orientation of the single grains. Different orientations of the optical axes will result in different colors of interference for optically uniaxial materials. The polarization micrographs themselves are already suitable for the analysis of the microstructure of CIM components regarding texture, separation planes, etc. Colorimetry is used in order to measure and describe the colors in a standardized color system. By means of color/orientation calibration curves that are measured with single crystal references, a quantitative description of the orientation of single grains as well as texturized areas can be obtained.
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Viney, Christopher, e Wendy S. Putnam. "Characterization of sheared liquid crystalline polymers by light microscopy". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 agosto 1993): 864–65. http://dx.doi.org/10.1017/s0424820100150150.
Abstract (sommario):
It is widely observed that nematic and cholesteric liquid crystalline materials develop a one-dimensional periodic microstructure during and/or after a uniaxial draw or simple shear (Fig. 1). This property is common to lyotropic and thermotropic examples of both small-molecule and polymeric liquid crystals. The periodic microstructure gives rise to a banded texture between crossed polars (Fig 2).A material under load will extend more readily if the microstructure contains crimps that can be straightened, compared to the extension that is achieved if covalent backbone bonds are highly aligned along the direction of load. The microstructure in Fig. 1 therefore is regarded as a stiffness-reducing defect. Two classes of stiff polymer that are produced from lyotropic solutions do not exhibit banded textures: the highest modulus variant of poly(p-phenyleneterephthalamide) (Kevlar), and various natural silk fibers. However, a banded texture is present in the less stiff variants of Kevlar, and also in silk fibers that have been drawn by hand from natural secretions, which demonstrates that the defect is not intrinsic to liquid crystalline molecular order, but is related to processing.
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Chaudry, Umer Masood, Kotiba Hamad e Tea-Sung Jun. "Investigating the Microstructure, Crystallographic Texture and Mechanical Behavior of Hot-Rolled Pure Mg and Mg-2Al-1Zn-1Ca Alloy". Crystals 12, n. 10 (21 settembre 2022): 1330. http://dx.doi.org/10.3390/cryst12101330.
Abstract (sommario):
In this study, the microstructure, crystallographic texture and the mechanical performance of hot-rolled pure Mg and Mg-2Al-1Zn-1Ca (herein inferred as AZX211) were thoroughly investigated. The results showed that the designed AZX211 alloy exhibited an exceptional strength/ductility synergy where an almost 40% increase in ductility was received for AZX211. The microstructural characterization revealed the grain refinement in the AZX211, where the grain size was reduced by more than 50% (24.5 µm, 10 µm for the pure Mg and the AZX211, respectively). Moreover, a discernible number of precipitates were dispersed in the AZX211, which were confirmed to be (Mg, Al)2Ca. The pure Mg showed a conventional strong basal texture while a significantly weakened split basal texture was received for the AZX211. The fraction of basal-oriented grains was 21% for the pure Mg and 5% for the AZX211. The significant texture weakening for the AZX211 can be attributed to the precipitation and co-segregation that triggered the preferential evolution of the non-basal grains while impeding the growth of the basal grains. This was also confirmed by the crystal orientation and the pseudo-rocking curves. The higher ductility of the AZX211 was explained based on the texture softening and Schmid factor for the basal and non-basal slip systems.
6
Zhang, Miao, e Shujie Liu. "Microstructure of laser cladding nickel-based superalloy: characterization, finite element modeling, and fatigue analysis". Journal of Physics: Conference Series 2184, n. 1 (1 marzo 2022): 012047. http://dx.doi.org/10.1088/1742-6596/2184/1/012047.
Abstract (sommario):
Abstract After laser cladding, the mechanical response of nickel-based single crystal superalloy is more complex when the loading direction is perpendicular to the columnar grain growth direction. In order to understand the deformation at grain level, a representative volume element (RVE) model based on the randomness of columnar grain texture was established for DD6 single crystal alloy, and the finite element model simulation of crystal plasticity (CPFEM) was performed. The results show that the stress and strain responses of the cladding microstructure are related to the grain distribution. The orientation difference between columnar grains in the epitaxial growth microstructure leads to non-uniform deformation and local stress concentration. The greater the crystal orientation difference is, the more obvious the stress concentration phenomenon is. On this basis, the statistical standard deviation of strain component is chosen to represent the fatigue damage of material, and the relationship between the statistical standard deviation of strain component and the external load strain is studied, which has certain reference value for the fatigue damage research of micro-cladding.
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Black, David R. "Microstructural characterization using x-ray diffraction imaging". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 agosto 1993): 504–5. http://dx.doi.org/10.1017/s0424820100148356.
Abstract (sommario):
X-ray diffraction imaging, also known as x-ray topography, is a powerful tool to study the defect microstructure of single crystals. As the name implies, this technique is based on recording an image of the diffracted x-ray beam from a crystal. Contrast in the image results from point-to-point variation in the diffracted intensity through the crystal. An example of a diffraction image is shown in figure 1. That this image is in some way a topographic representation of the sample can be seen in the impression of differing elevations and textures in different parts of the image. However, since this image is a result of diffraction from the sample the interpretation of the image is much more complex.Diffraction contrast is usually separated into two types: mosaic contrast and extinction contrast. Mosaic contrast occurs for crystals considered to be formed from a collection of small perfect crystal blocks. These blocks have a well defined rocking curve width, the angular range over which they will diffract, and may be slightly misoriented with respect to each other and/or may have different lattice spacing.
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DiMasi, E., e M. Sarikaya. "Synchrotron x-ray microbeam diffraction from abalone shell". Journal of Materials Research 19, n. 5 (maggio 2004): 1471–76. http://dx.doi.org/10.1557/jmr.2004.0196.
Abstract (sommario):
Microstructured biomaterials such as mollusk shells receive much attention at present, due to the promise that advanced materials can be designed and synthesized with biomimetic techniques that take advantage of self-assembly and aqueous, ambient processing conditions. A satisfactory understanding of this process requires characterization of the microstructure not only in the mature biomaterial, but at the growth fronts where the control over crystal morphology and orientation is enacted. In this paper, we present synchrotron microbeam x-ray diffraction (XRD) and electron microscopy observations near the nacre–prismatic interface of red abalone shell. The relative orientations of calcite and aragonite grains exhibit some differences from the idealizations reported previously. Long calcite grains impinge the nacre–prismatic boundary at 45° angles, suggestive of nucleation on (104) planes followed by growth along the c axis. In the region within 100 μm of the boundary, calcite and aragonite crystals lose their bulk orientational order, but we found no evidence for qualitative changes in long-range order such as ideal powder texture or an amorphous structure factor. XRD rocking curves determined the mosaic of calcite crystals in the prismatic region to be no broader than the 0.3° resolution limit of the beamline’s capillary optics, comparable to what can be measured on geological calcite single crystals.
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Claves, Steven R., Wojciech Z. Misiolek, William H. Van Geertruyden e David B. Williams. "Use of Electron Backscatter Diffraction Technique in Characterization of 6XXX Aluminum Alloy Extrusions". Microscopy and Microanalysis 6, S2 (agosto 2000): 954–55. http://dx.doi.org/10.1017/s1431927600037260.
Abstract (sommario):
Electron Backscattering Diffraction (EBSD) is an important tool for analyzing the crystal grain orientation of a microstructure and can be used to formulate conclusions about microtexture, texture determined from individual grains. This technique has been used to study a 6xxx series aluminum alloy's response to the deformation of the extrusion process. Extrusion is the process by which a billet of material is forced, under high pressure, through a die. The material undergoes a significant decrease in cross sectional area, and is formed into a shape equivalent to the geometry of the die orifice. Different bearing lands are shown in shown in Figure 1. These surfaces form the part, and are designed to control the metal flow making it uniform through the die, thus yielding good mechanical properties. This research was focused on the resultant microstructure. The shaded regions of Figure 2 show the two surface regions where EBSD measurements were taken.
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Habibi, Niloufar, Napat Vajragupta e Sebastian Münstermann. "Deformation and Damage Assessments of Two DP1000 Steels Using a Micromechanical Modelling Method". Crystals 11, n. 7 (10 luglio 2021): 805. http://dx.doi.org/10.3390/cryst11070805.
Abstract (sommario):
Damage characterization and micromechanical modelling in dual-phase (DP) steels have recently drawn attention, since any changes in the alloying elements or process route strongly influence the microstructural features, deformation behavior of the phases, and damage to the micro-mechanisms, and subsequently the particular mechanical properties of the material. This approach can be used to stablish microstructure–properties relationships. For instance, the effects of local damage from shear cutting on edge crack sensitivity in the following deformation process can be studied. This work evaluated the deformation and damage behaviors of two DP1000 steels using a microstructure-based approach to estimate the edge cracking resistance. Phase fraction, grain size, phase distribution, and texture were analyzed using electron backscatter diffraction and secondary electron detectors of a scanning electron microscope and employed in 3D representative volume elements. The deformation behavior of the ferrite phase was defined using a crystal plasticity model, which was calibrated through nanoindentation tests. Various loading conditions, including uniaxial tension, equi-biaxial tension, plane strain tension, and shearing, along with the maximum shear stress criterion were applied to investigate the damage initiation and describe the edge cracking sensitivity of the studied steels. The results revealed that a homogenous microstructure leads to homogenous stress–strain partitioning, delayed damage initiation, and high edge cracking resistance.
Tesi sul tema "Microstructure and crystal texture characterization":
1
Khabouchi, Amal. "Microstructure, texture et propagation des ondes ultrasonores dans un superalliage à base de nickel fait par fabrication additive". Electronic Thesis or Diss., Université de Lorraine, 2021. https://docnum.univ-lorraine.fr/public/DDOC_T_2021_0349_KHABOUCHI.pdf.
Abstract (sommario):
La fabrication additive est une technique industrielle révolutionnaire qui suscite un intérêt croissant depuis la fin des années 80 et commence petit à petit à remplacer les procédés conventionnels de fabrication, et même à ouvrir des horizons sur la création de nouveaux types de matériaux.Cette importance lui est attribuée grâce à plusieurs spécificités, à savoir la possibilité presque infinie de construire des pièces avec des géométries complexes et la possibilité de mixer plusieurs types de poudres avec des compositions chimiques différentes pour obtenir des matériaux à propriétés bien déterminées selon l’application finale. Ces matériaux sont souvent appelés matériaux à gradation fonctionnelle (functionally graded materials). La fabrication additive permet même de construire des matériaux composites. Elle est à présent utilisée dans presque tous les domaines industriels : aérospatial, médical, automobile ainsi que celui des composants électroniques. L’extension de la fabrication additive aux alliages métalliques est encore plus récente. Au cours des vingt dernières années, de nombreux procédés de fabrication additive métallique ont été développés. On peut citer la fusion laser sur lit de poudre (appelée SLM ou L-PBF), la Construction Laser Additive Directe (CLAD), le frittage sélectif sous laser (SLS), etc. … Bien qu’elle soit une technique très prometteuse, la fabrication additive, surtout la métallique, reste encore mal maîtrisée. Un gros travail technologique a été réalisé pour optimiser les paramètres de fabrication et améliorer les propriétés, notamment mécaniques, des pièces produites. Pour pouvoir exploiter à fond les atouts de la technique, un important effort de recherche reste cependant à faire pour bien comprendre et contrôler les mécanismes fins mis en jeu par les procédés. En conséquence, la communauté scientifique est actuellement très active dans ce domaine et les publications très nombreuses. D’un point de vue métallurgique, deux points apparaissent primordiaux pour la tenue mécanique des pièces. D’une part la présence de porosités, en plus ou moins forte proportion, dans le matériau déposé, qui peut conduire à une diminution de sa résistance. D’autre part, la texturation cristalline inhérente au procédé utilisé, qui se traduit par un comportement mécanique anisotrope. Les travaux de cette thèse se situent dans ce contexte. Ils ont été menés dans le cadre d’une collaboration entre le LEM3 de Metz et le CEA-LIST de Saclay, intégrée dans un programme de recherche et d’innovation plus large liant le CEA-Tech de Lorraine et la Région Lorraine. Le CEA-LIST est spécialisé -entre autres- dans le développement de méthodes de contrôle non destructif (CND) pour détecter la présence de défauts dans des pièces métalliques. Le LEM3 a une compétence particulière dans la quantification et la compréhension des textures cristallines des alliages métalliques liées à leurs conditions d’élaboration. D’un point de vue scientifique, les objectifs de la thèse étaient doubles : d’une part améliorer notre compréhension de la genèse des textures cristallines lors du dépôt d’un alliage métallique par SLM ; d’autre part, évaluer les conséquences de ces textures sur la propagation des ondes ultrasonores utilisées classiquemen t en CND. D’un point de vue plus pratique, la question qui se posait en début de thèse était : l’anisotropie de propagation élastique des ultrasons liée à la texturation cristalline produite par le procédé SLM nécessite-t-elle de revoir le protocole de contrôle non destructif par ultrasons ?Additive Manufacturing is a revolutionary industrial technique that has attracted increasing interest since the late 1980s and is gradually beginning to replace conventional manufacturing processes, and even to open horizons for the creation of new types of materials. This importance is attributed to it thanks to several specificities, namely the almost infinite possibility of building parts with complex geometries and the possibility of mixing several types of powders with different chemical compositions to obtain materials with well-defined properties depending on the final applications. These materials are often referred to as functionally graded materials. Additive manufacturing is even used to build composite materials. It is now used in almost all industrial fields: aerospace, medical, automotive and electronic components. The extension of additive manufacturing to metal alloys is even more recent. Over the past 20 years, many metal additive manufacturing processes have been developed. Examples include laser powder bed fusion (called SLM or L-PBF), direct additive laser construction (CLAD), selective laser sintering (SLS), etc... Although that it is a very promising technique, additive manufacturing, especially the metallic one, is still poorly controlled. Considerable technological work has been done to optimise the manufacturing parameters and improve the properties, particularly mechanical ones, of the parts produced. However, to fully use the advantages of the technique, a major research effort remains to be made to fully understand and control the fine mechanisms involved in the processes. As a result, the scientific community is currently very active in this field and the publications are very numerous. From a metallurgical point of view, two points seem to be important for the mechanical strength of the parts. On one hand, the presence of porosities, in a greater or lesser proportion, in the deposited material, which can le ad to a decrease in its resistance. On the other hand, the crystalline texturing inherent in the process used, which results in an anisotropic mechanical behaviour. The work of this thesis is in this context. It was conducted as part of a collaboration between the LEM3 in Metz and CEA-LIST in Saclay, integrated within a wider program of research and innovation joining CEA-Tech Lorraine and the Region of Lorraine. The CEA-LIST is specialized -among other things- in the development of non-destructive control methods (NDT) to detect the presence of defects in metal parts. LEM3 has particular competence in quantifying and understanding the crystalline textures of metal alloys related to their elaboration conditions. From a scientific point of view, the objectives of the thesis were twofold: on the one hand, our objective was to improve our understanding of the genesis of crystalline textures during the deposit of a metal alloy by SLM; On the other hand, we aim to evaluate the consequenc es of these textures on the propagation of the ultrasound waves which are traditionally used in CND. From a more practical point of view, the question that arose at the beginning of the thesis was: does the elastic anisotropy of propagation of ultrasound linked to the crystalline texturing produced by the SLM process require a review of the protocol of non-destructive control by ultrasound?
2
Mandal, Sudipto. "Texture and Microstructure in Two-Phase Titanium Alloys". Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1024.
Abstract (sommario):
This work explores the processing-microstructure-property relationships in two-phase titanium alloys such as Ti-6Al-4V and Ti-5Al-5V-5Mo-3Cr that are used for aerospace applications. For this purpose, an Integrated Computational Materials Engineering approach is used. Microstructure and texture of titanium alloys are characterized using optical microscopy, electron backscatter diffraction and x-ray diffraction. To model their properties, threedimensional synthetic digital microstructures are generated based on experimental characterization data. An open source software package, DREAM.3D, is used to create heterogeneous two-phase microstructures that are statistically representative of two-phase titanium alloys. Both mean-field and full-field crystal plasticity models are used for simulating uniaxial compression at different loading conditions. A viscoplastic self-consistent model is used to match the stress-strain response of the Ti-5553 alloy based on uniaxial compression tests. A physically-based Mechanical Threshold Stress (MTS) model is designed to cover wide ranges of deformation conditions. Uncertainties in the parameters of the MTS model are quantified using canonical correlation analysis, a multivariate global sensitivity analysis technique. An elastoviscoplastic full-field model based on the fast Fourier transform algorithm was used to used to simulate the deformation response at both microscopic and continuum level. The probability distribution of stresses and strains for both the phases in the two-phase material is examined statistically. The effect of changing HCP phase volume fraction and morphology has been explored with the intent of explaining the ow softening behavior in titanium alloys.
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Brunet, Frédéric. "Texture et microstructure de films de diamant : effet du dopage au bore". Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10176.
Abstract (sommario):
Le diamant presente des proprietes physiques intrinseques extremement attractives qui sont notamment appropriees pour des applications electroniques. Cependant, il convient de rester prudent car les caracteristiques globales des films (purete de la phase diamant, tailles des cristallites, epaisseur, morphologie, texture, contraintes internes etc. . . ) dependent fortement des conditions de croissance et conditionnent les proprietes des films. L'analyse quantitative de la texture (logiciel d'analyse de texture beartex) de films de diamant polycristallins deposes sur substrat de silicium par mpcvd a permis d'estimer l'influence des parametres d'elaboration (temperature du substrat, 650-880c, taux de methane, 0. 3%-2%), de l'epaisseur des films (jusqu'a 70 m) et du taux d'incorporation de bore (jusqu'a 5x10#2#0 b-cm#-#3) sur le developpement d'une orientation preferentielle au cours de la croissance. L'analyse du profil des raies de diffraction a permis d'etudier l'influence du dopage au bore sur la microstructure des films polycristallins. Les resultats issus des methodes des largeurs integrales, de fourier et de la variance indiquent une evolution (amelioration jusqu'a 10#1#9 b-cm#-#3 puis deterioration) de la qualite cistalline des films avec le dopage. Une etude structurale conjointement menee sur des films polycristallins et monocristallins deposes respectivement sur substrat de silicium et de diamant monocristallins montre que le parametre cristallin du diamant augmente avec le dopage au bore. La dilatation atteint 0. 2% pour un dopage de 8x10#2#0 b-cm#-#3 et devient significative au dela de la transition semiconducteur-metal.
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Bastos, da Silva Fanta Alice. "Characterization of the microstructure, grain boundaries and texture of nanostructured electrodeposited CoNi by use of electron backscatter diffraction (EBSD)". Göttingen Cuvillier, 2007. http://d-nb.info/991032845/04.
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Bastos, da Silva Fanta Alice. "Characterization of the microstructure, grain boundaries and texture of nanostructured electrodeposited CoNi by use of Electron Backscatter Diffraction (EBSD) /". Göttingen : Cuvillier, 2008. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=017078787&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Niyonzima, Jean de dieu. "Topological defects in smectic A liquid crystal thin films". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS660.pdf.
Abstract (sommario):
En raison de leur nature omniprésente et polyvalente, les défauts topologiques suscitent un grand intérêt depuis plus d'un siècle dans différents domaines de recherche tels que la cosmologie, la biologie et la physique de la matière condensée. Ils jouent un rôle important dans la détermination des propriétés dynamiques et statiques des matériaux qui les hébergent. Les défauts topologiques des cristaux liquides Smectic A se sont révélés capables d'attirer, de piéger et d'orienter les nanoparticules dans différents réseaux au cœur de leurs défauts. Cependant, la structure locale des défauts topologiques reste en général mal connue. Les films minces de cristaux liquides smectiques confinés qui peuvent conduire facilement à la formation de défauts topologiques sont utiles dans ce cadre car ils permettent d'utiliser la diffusion des rayons X pour les étudier avec une résolution sans précédent. En utilisant la diffusion des rayons X aux petits angles en incidence rasante (GISAXS) sur la ligne de faisceau SIXS du Synchrotron Soleil, nous avons étudié la structure interne d'un réseau de défauts topologiques smectiques orientés dans des films minces de cristaux liquides smectiques A de 4-n-octyl-4'-cyanobiphényle (8CB) confinés entre deux ancrages antagonistes forts imposés par le substrat d'alcool polyvinylique (planaire unidirectionnel) et l'air (perpendiculaire). Ces films sont composés de couches smectiques superposées en hémicylindres aplatis. Nous avons déterminé théoriquement la relation entre l'intensité de Bragg intégrée, la largeur maximale à mi-hauteur du pic diffusé et le nombre de couches smectiques qui tournent au sein des hémicylindres. Cela nous a permis de reconstruire avec précision la structure interne de ces films minces. Nous avons démontré que trois types différents de défauts topologiques coexistent à l'intérieur de ces films minces smectiques, des dislocations, des disinclinaisons et des joints de grains topologiques bidimensionnels tous orientés dans la direction parallèle à l'axe des hémicylindres. Les couches smectiques qui relient tous ces défauts présentent une dilatation anormalement forte de la distance inter-couches à proximité du centre de courbure des hémicylindres. Une minimisation de l'énergie élastique conduit à une relation quantitative entre cette distance et le rayon de courbure des couches smectiques en parfait accord avec les données expérimentales. Cette dilation est à l'origine non seulement de la formation des dislocations mais aussi de la formation d'un chevron au milieu des hémicylindres. Nous avons ensuite analysé l'évolution des structures en fonction de l'épaisseur du film. Nous avons constaté que c’est essentiellement la zone de disinclinaison qui gère le changement de structure quand l'épaisseur augmente à cause de la nécessité de diminuer l'énergie de surface du film smectique. Cela nous a permis de montrer en particulier comment la taille du cœur de disclinaison peut être contrôlée par l'épaisseur du film smectiqueDue to their ubiquitous and versatile nature, the topological defects have been the subject of a great interest for over a century in different research areas such as cosmology, biology and condensed matter physics. They are important in the determination of dynamic and static properties of the material that host them. Smectic A liquid crystal topological defects have been shown to be able to attract, trap and orient nanoparticle into different networks in their defect cores. However, their intimate structure remains elusive. Liquid crystals are laboratory systems to study topological defects. The confined smectic liquid crystal thin films that can lead to the formation of topological defects are useful since they allow for the use of X-ray scattering to study the defects at an unprecedented resolution. Using Grazing Incident Small-Angle X-ray Scattering (GISAXS) on the SIXS beamline of Soleil Synchrotron facility, we studied the internal structure of an array of oriented smectic topological defects in thin smectic-A liquid crystal films of of 4-n-octyl-4’-cyanobiphenyl (8CB) confined between two strong antagonistic anchoring imposed by Polyvinyl alcohol substrate (planar unidirectional) and air (homeotropic). We studied a film of 180 nm thickness and found that it is composed of smectic layers superimposed into flattened hemicylinders. We have theoretically determined the relationship between the integrated Bragg intensity, the Full width at Half maximum of the scattered peak and the number of scattering rotating smectic layers. This allowed us to reconstruct with precision the internal structure of these thin smectic films. We have evidenced that three different kinds of topological defects coexist inside these thin smectic films, dislocations, disclination and 2D topological grain boundaries, all oriented in the direction parallel to the axis of the hemicylinders. The rotating smectic layers that connect these defects display an unusually strong increase of their interlayer spacing close to the hemicylinder curvature center. A minimization of the elastic energy leads to a quantitative relationship between the interlayer spacing and the curvature radius of the smectic layers in perfect agreement with the experimental data. This interlayer spacing appears to be not only at the origin of the dislocation formation but also at the origin of a chevron formation in the middle of the hemicylinders. We have then analyzed the evolution of the structures as a function of the film thickness. We found that it is essentially the disinclination zone that manages the change in structure as the thickness increases due to the need to decrease the surface energy of the smectic film. This allowed us to show in particular how the size of the disclination core can be controlled by the thickness of the smectic film
7
Chen, Zhe. "Relation microstructure et propriété mécanique des films de ZrO2 obtenus par MOCVD". Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00637177.
Abstract (sommario):
Les films de ZrO2 pur sont déposés par MOCVD (Metal-Organic Chemical Vapor Deposition) en variant de nombreux paramètres du processus. L'influence des conditions de dépôt sur l'évolution de la microstructure (morphologies, structure cristalline/phase, texture et contrainte résiduelle) a été étudiée et clarifiée. Par des analyses approfondies des résultats expérimentaux, trois mécanismes typiques de croissance de dépôt de ZrO2 ont été proposées. Les contraintes de croissance de compression sont en relation directe avec la diffusion atomique et la quantité d'espèces piégées dans les films. La formation de la texture cristallographique est complexe et deux types de textures ont été analysées dans la phase tétragonale : la texture de fibre {1 1 0}t est contribuée par l'effet superplastique des nano-cristallites de ZrO2 et par la contrainte de croissance de compression ; tandis que la morphologie en facette est due à la croissance concurrentielle de différents plans cristallographiques. La stabilisation de la phase tétragonale de ZrO2 a été analysée et discutée. En plus de la taille critique des cristallites, la stabilisation de la phase tétragonale est favorisée par deux autres mécanismes : la grande quantité des défauts cristallins et la morphologie des cristallites.
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Bernier, Jeremy Scott. "Evolution and Characterization of Partially Stabilized Zirconia (7wt% Y2O3) Thermal Barrier Coatings Deposited by Electron Beam Physical Vapor Deposition". Digital WPI, 2002. https://digitalcommons.wpi.edu/etd-theses/826.
Abstract (sommario):
Thermal barrier coatings (TBCs) of ZrO2-7wt% Y2O3 were deposited by electron beam physical vapor deposition (EB-PVD) onto stationary flat plates and cylindrical surfaces in a multiple ingot coater. Crystallographic texture, microstructure, and deposition rate were investigated in this thesis. The crystallographic texture of EB-PVD TBCs deposited on stationary flat surfaces has been experimentally determined by comparing pole figure analysis data with actual column growth angle data. It was found that the TBC coating deposited directly above an ingot exhibits <220> single crystal type crystallographic texture. Coatings deposited between and off the centerline of the ingots the exhibited a <311>-type single crystal texture. For coatings deposited in the far corners of the coating chamber either a <111> fiber texture or a <311> single crystal type texture existed. The crystallographic texture of EB-PVD TBCs deposited on cylindrical surfaces was characterized using x-ray diffraction (XRD) at different angular positions on the cylinder substrate. XRD results revealed that crystallographic texture changes with angular position. Changes in crystallographic texture are attributed to the growth direction of the columns and substrate temperature. Growth direction is controlled by the direction of the incoming vapor flux (i.e. vapor incidence angle), in which competition occurs between crystallites growing at different rates. The fastest growing orientation takes over and dominates the texture. Substrate temperature variations throughout the coating chamber resulted in different growth rates and morphology. Morphology differences existed between cylindrical and flat plate surfaces. Flat cross sectional surfaces of the coatings exhibited a dense columnar structure in which the columns grew towards the closest vapor source. Surface features were found to be larger for coatings deposited directly above an ingot than coatings deposited away from the ingots. Morphological differences result from substrate temperature changes within the coating chamber, which influences growth kinetics of the coating. Cylindrical surfaces revealed a columnar structure in which columns grew towards the closest vapor. Porosity of the coating was found to increase when the angular position changed from the bottom of the cylinder. Change in angular position also caused the column diameter to decreases. Morphology changes are attributed to self-shadow effects caused by the surface curvature of the cylinder and vapor incidence angle changes. Overall, the microstructure and crystallographic texture of EB-PVD coatings was found to depend on the position in the coating chamber which was found to influence substrate temperature, growth directions, and shadowing effects. The coating thickness profiles for EB-PVD TBCs deposited on stationary cylinders have been experimentally measured and theoretically modeled using Knudsen's cosine law of emissions. A comparison of the experimental results with the model reveals that the model must to be modified to account for the sticking coefficient as well as a ricochet factor. These results are also discussed in terms of the effects of substrate temperature on the sticking coefficient, the ricochet factor, and coating density.
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Barrat, Sylvère. "Caractérisations morphologiques, chimiques, et structurales de cristaux et films de diamant élaborés par un procédé de dépôt chimique en phase vapeur assisté par plasma micro-onde". Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_BARRAT_S.pdf.
Abstract (sommario):
La possibilité de synthétiser du diamant dans des conditions métastables, qui ne nécessitent pas des valeurs extrêmes de température et de pression, et les perspectives d'applications dans les domaines de la mécanique, de l'optique et de l'électronique, nous ont conduits à concevoir un réacteur MPCVD (dépôt chimique en phase vapeur assisté par plasma micro-onde), dans lequel nous avons élaboré des cristaux et des films de diamant. Dans un premier temps, nous nous sommes attachés à caractériser la morphologie des cristaux de diamant par microscopie électronique à balayage, et leur qualité chimique par spectroscopie Raman, en fonction des conditions d'élaboration. Nous avons ainsi mis en évidence une détérioration cristalline, qui se produit lorsque la teneur en hydrocarbure s'élève, et lorsque la température augmente. Par la suite, l'optimisation du réacteur, et en particulier une localisation plus précise de la décharge, a conduit à l'élaboration de dépôts homogènes constitués de cristaux développant des faces {100} et {111}. Cette optimisation nous a donné les moyens de réaliser une analyse morphométrique de ces cristaux, qui permet de suivre quantitativement l'évolution de la morphologie des monocristaux et des particules multimaclées (MTP), en fonction de la température du substrat et de la teneur en méthane. Un prétraitement adapté des substrats de silicium, nous a permis d'élever la densité de germes afin d'élaborer des films de diamant. Leur caractérisation microstructurale par microscopie électronique à transmission, a mis en évidence une répartition particulière des défauts structuraux présents uniquement selon les faces {111}, et a révélé la microstructure des MTP. Afin d'améliorer la qualité des films de diamant, nous avons élaboré des films épais texturés, définis par une morphologie globale décrivant l'axe de fibre et la nature des faces cristallines présentes en surface. En utilisant les résultats de l'analyse morphométrique, et en complétant le modèle de croissance généralement admis pour le diamant CVD, il a été possible de prévoir la morphologie globale des dépôts en fonction des conditions de synthèse, et d'élaborer des films où la quantité et la répartition des défauts structuraux sont en partie maitrisées
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Missaoui, Amine. "Dynamics of topological defects in freely floating smectic liquid crystal films and bubbles". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS207.
Abstract (sommario):
L'objectif de la thèse est d'étudier la dynamique des défauts topologiques dans les cristaux liquides (LC). Parmi le large éventail de choix possibles, nous nous intéressons à la phase cristalline liquide thermotropique smectique-C. La propriété unique de cette phase LC permet de former des films librement suspendus, qui sont supportés sur un support et délimités par un ménisque, et des bulles flottant librement. Les études dans ces systèmes en suspension sont d'une part moins influencées par les conditions limites qui existent dans le cas des cellules LC et d'autre part plus faciles à interpréter grâce à la géométrie bidimensionnelle de ces films et bulles. L'objectif consiste à exploiter les propriétés des films et des bulles en suspension libre de la smectique-C pour l'étude de la dynamique des défauts topologiquesThe aim of the thesis is to study the dynamics of topological defects in liquid crystals (LC). Among the wide range of possible choices, we are interested in the thermotropic smectic-C liquid crystalline phase. The unique property of this LC phase allows to form freely suspended films, that are supported on a holder and bounded by a meniscus, and freely floating bubbles. The studies in these suspended systems are on the one hand less influenced by the boundary conditions that exist in the case of the LC cells and on the other hand easier to interpret thanks to the two-dimensional geometry of these films and bubbles. The aim of the PhD consists in exploiting the properties of smectique-C freely suspended films and bubbles for the study of the dynamics of topological defects
Libri sul tema "Microstructure and crystal texture characterization":
1
Novikov, V. I͡U. Grain growth and control of microstructure and texture in polycrystalline materials. Boca Raton: CRC Press, 1997.
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Zhu, Xingwen. ZnO bao mo zhi bei ji qi guang, dian xing neng yan jiu. 8a ed. Shanghai Shi: Shanghai da xue chu ban she, 2010.
Capitoli di libri sul tema "Microstructure and crystal texture characterization":
1
Van Houtte, Paul. "Crystal Plasticity Based Modelling of Deformation Textures". In Microstructure and Texture in Steels, 209–24. London: Springer London, 2009. http://dx.doi.org/10.1007/978-1-84882-454-6_12.
2
Rollett, Anthony D., Sukbin Lee e Ricardo A. Lebensohn. "3D Image-Based Viscoplastic Response with Crystal Plasticity". In Microstructure and Texture in Steels, 255–64. London: Springer London, 2009. http://dx.doi.org/10.1007/978-1-84882-454-6_15.
3
Arenz, Uwe, e Eckhardt Schneider. "Microstructure and Texture Influences on Ultrasonic Quantities for Welding Stress Analysis". In Nondestructive Characterization of Materials VIII, 653–58. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-4847-8_102.
4
Chadha, K., P. P. Bhattacharjee e M. Jahazi. "The Effect of Strain Reversal during High Pressure Torsion on the Microstructure Evolution and Texture of Aluminum Alloys". In Characterization of Minerals, Metals, and Materials 2015, 107–14. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48191-3_13.
5
Baroghel-Bouny, Véronique, e Thierry Chaussadent. "Texture and Moisture Characterization of Hardened Cement Pastes and Concretes from Water Vapour Sorption Measurements". In The Modelling of Microstructure and its Potential for Studying Transport Properties and Durability, 241–55. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8646-7_11.
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Ishida, Naoki, Daisuke Terada, Keizo Kashihara e Nobuhiro Tsuji. "Evolution of Microstructure and Texture of Pure Al Single Crystal Having {112}<110> Orientation during Severe Plastic Deformation". In Advanced Materials Research, 405–8. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-463-4.405.
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Vizcaino, Pablo, Alejandra V. Flores, Miguel A. Vicente Alvarez, Javier R. Santisteban, Gladys Domizzi, Alfredo Tolley, Adriana Condó e Jonathan D. Almer. "Characterization of Hydrides and the α-Zr Matrix in Zirconium Alloys: Effects of Stresses, Microstructure, and Neutron Irradiation on Hydride Texture, Terminal Solid Solubility, and Dislocation Structure". In Zirconium in the Nuclear Industry: 19th International Symposium, 786–811. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2021. http://dx.doi.org/10.1520/stp162220190019.
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Araceli, SALAZAR-PERALTA, PICHARDO-SALAZAR José Alfredo, SÁNCHEZ-OROZCO Raymundo e PICHARDO-SALAZAR Ulises. "Introduction to Metallographic Study". In Handbook Science of Technology and Innovation, 106–29. ECORFAN, 2022. http://dx.doi.org/10.35429/h.2022.3.106.129.
Abstract (sommario):
The quality assurance of materials in every process depends on materials science and engineering, since the characterization of materials is a fundamental process, for their control and innovation, as well as their proper functioning. In the synthesis of new materials, their properties depend not only on the type of raw material used (metal, polymer, ceramic, composite material), but also on the morphology acquired in the synthesis, structure, microstructure, etc. of the material obtained, hence the importance of metallographic characterization. Metallography is the science that deals with the microscopic study of the structural characteristics of a metal or an alloy, to study the microstructure, inclusions, as well as the thermal treatments to which the material has been subjected, in order to determine if the material complies with the specifications established in the Standards applicable to the design requirements for a specific use. The objective of this study was to present the basic techniques for the preparation of specimens to be evaluated metallographically, addressing the following topics: Generalities, Atomic structure: Nucleation and atoms, Crystal structure: Perfect crystals and crystals with imperfections. Substructure: Subgrains and other cellular structures, Microstructure: Grains of single metallic phases and configuration arrangements of alloys with multiple phase systems, Texture. Macrostructure. and Metallographic practice applicable to all metals. It is concluded that this study lays the foundations for subsequent and specific metallographic studies of ferrous and non-ferrous alloys.
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Raabe, Dierk. "Texture–Property Relationships in Aluminum Alloys: Simulations and Experiments". In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000443.
Abstract (sommario):
Aluminum alloys provide a huge and increasing application spectrum for formed and cast products. This article texture and anisotropy of aluminum alloys. Topics covered include: experimental determination of surface strains, nanotextures and microtextures, constitutive laws for crystal plasticity finite element simulations and cellular automata for recrystallization, microscopic aspects of texture evolution during plastic deformation and recrystallization, relationship between texture, microstructure and surface properties, integration anisotropy into metal-forming simulations, and crystallographic approximation elastic-plastic anisotropy.
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LÓPEZ, Roberto, Jesús NAMIGTLE e Jorge MASTACHE. "Structural characterisation of copper oxide by X-ray diffraction". In Handbooks Engineering Science and Technology TIX, 70–96. ECORFAN, 2021. http://dx.doi.org/10.35429/h.2021.9.1.70.96.
Abstract (sommario):
In this work, the study of the structural characterization of copper oxide by the X-ray diffraction technique is presented. To obtain layers of copper oxide, sputtering and thermal oxidation techniques were combined. The average crystal size was calculated for the sputtered copper samples. For the copper oxide films obtained by thermal oxidation, both the crystal size and the texture coefficient were calculated. The crystalline quality was poor for layers obtained by sputtering. Thermal oxidation carried out on these films transformed its structure to the copper oxide phase known as cupric oxide.
Atti di convegni sul tema "Microstructure and crystal texture characterization":
1
KAVOUSI, Majid. "Cellular automata and crystal plasticity modelling for metal additive manufacturing". In Material Forming. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644903131-267.
Abstract (sommario):
Abstract. This paper presents a methodology to establish a process-structure-property (PSP) relationship for the additive manufacturing (AM) of small AISI 316L parts, as might be used in coronary stent applications. The methodology includes a physically based process-structure model based on cellular automata (CA) for microstructure characterization and generation, coupled with crystal plasticity finite element (CPFE) structure-property modelling to predict the mechanical response of the AM part under tensile loading. The effect of AM process variables, such as laser power and scanning speed, are reflected in the PSP modelling through the thermal modelling of AM feeding into the CA model. The CA method is shown to be able to capture microstructure texture, which is key to anisotropic behavior of AM parts. The present study aims to (i) establish a practical link between CA and CPFE models and (ii) identify optimal process variables with respect to ductility.
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MISHRA, BIDYAPATI, B. RAMAKRISHNA, K. SIVA KUMAR e V. MADHU. "High Strain Rate Deformation Behavior of Materials: Effect of Crystal Structure, Grain Size, Microstructure and Texture". In 31st International Symposium on Ballistics. Lancaster, PA: DEStech Publications, Inc., 2019. http://dx.doi.org/10.12783/ballistics2019/33215.
3
Parasız, Sunal Ahmet, Brad L. Kinsey, Neil Krishnan e Jian Cao. "Characterization and Investigation of Deformation During Microextrusion Using X-Ray Texture Analyses". In ASME 2007 International Manufacturing Science and Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/msec2007-31107.
Abstract (sommario):
In microforming scaling down the size of the process while the grain size is kept relatively constant usually results in inhomogeneous deformation. In most works, the inhomogeneous deformation of miniaturized samples is presented and evaluated by microstructure analyses of the deformed grains. However, in certain microforming processes, such as microextrusion, where the final texture of the conventional macro size samples is well known, texture analyses can provide useful information about the deformation. In our past research, extrusion experiments were performed to produce sub-millimeter sized pins having a base diameter of 0.76 mm and an extruded diameter of 0.57 mm. Curvature of differing degrees and directions was observed in workpieces with a coarse grain size of 211 μm. However, a similar effect did not occur in workpieces with a fine grain size of 32 μm. Microstructure analyses showed that when the sample size approaches the grain size, the deformation becomes inhomogeneous and the properties of individual grains can dominate the overall deformation of their cross-sections. Moreover, microhardness measurements revealed that deformation size effects are present and as a result the coarse grained pins strain hardened more than the fine grained pins during microextrusion. This result along with microstructure analyses suggested that the coarse grains in the central region possibly undergo more shear deformation. In this paper, X-ray texture analyses of the pins were performed to validate that there is penetration of shear deformation into the central regions of the coarse grained pins. Also, the texture analyses point to the possibility that the deformation in the curved region of the coarse grained pins is not axially symmetric which causes the curvature observed.
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Ma, Xianfeng, Kan Ma e Yawen Wu. "Crystal Plasticity Modeling of Hot Extrusion Texture and Plasticity in a Titanium Alloy for an ICME Toolset". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67989.
Abstract (sommario):
For a better use of titanium alloy in nuclear industry, development of integrated computational materials engineering (ICME) model is necessary to optimize alloy microstructure and thus the performance of titanium component. Within an ICME toolset, constitutive models play an important role in quantitatively capturing the interrelationship between processing, microstructure and property. In this paper, texture evolution during hot extrusion of near-alpha Ti6242S bar were studied with respect to the deformation and transformation texture component. Experimentally measured alpha and beta phase textures were instantiated in a three dimensional rate-dependent crystal plasticity model. The model is able to accurately predict the deformation textures of both the alpha and beta phases at extrusion temperature. While decomposition of the metastable beta phase occurred during the post-extrusion cooling, most of the transformation texture components formed aligned [0001] with the extrusion direction, which formed the primary component of extruded alpha texture. The transformation texture was predicted by numerically decomposing the simulated beta texture according to appropriate variant selection rule. Also demonstrated was the capability of a crystal plasticity model incorporating microstructure information, such as phase fraction and lamellar spacing. The crystal plasticity model was validated by comparing with the experimental elastoplasticity behaviors of Ti6242S bars with various microstructures.
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Wang, Zhiyu, Christopher Saldana e Saurabh Basu. "Subsurface Microstructure and Crystallographic Texture in Surface Severe Plastic Deformation Processes". In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2915.
Abstract (sommario):
Severe plastic burnishing was investigated as a promising surface severe plastic deformation technique for generating gradient microstructure surfaces. The deformed state of oxygen free high conductivity copper workpieces during the surface deformation process was determined with high-speed imaging, this complemented by microstructure characterization using orientation image microscopy based on electron backscatter diffraction. Varying deformation levels in terms of both magnitude and gradient on the processed surface were achieved through control of the incident tool angle. Refined microstructures, including laminate grains elongated in the velocity direction and equiaxed sub-micron grains were observed in the subsurface and were found to be controlled by the combined effects of strain and strain rate in the surface deformation process. Additionally, crystallographic texture evolutions were characterized, showing typical shear textures predominately along the <110> partial fiber. The rotation of texture from original ideal orientation positions was related directly to the deformation history produced by sliding process. Based on these observations, a controllable framework for producing the processed surface with expected mechanical and microstructural responses is suggested.
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Zhao, Man, e Steven Y. Liang. "Modeling of Residual Stress in Micro-Grinding Considering Texture Effect". In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69724.
Abstract (sommario):
Abstract Residual stress is an important mechanical property parameter and a key evaluation index of the surface integrity. Residual stress induced in micro-grinding is related to the process parameters, the wheel properties, and material microstructure. The micro-grinding process is distinct from the conventional grinding owing to size effect, and the crystal effect. Typically, the effects of crystallographic orientation (CO) on process behaviors are significant by influencing the flow stress of workpiece material due to the depth of cut is usually less than the average grain size. In this paper, a Taylor factor model is developed to estimate the effect of CO on the flow stress and plastic modulus of monocrystalline materials. The flow stress model takes into account strain, strain rate, temperature, and material microstructure including grain size, CO, and dislocation density. The plastic modulus of monocrystalline materials h is given as the function of hardness, strain, and microstructure. The analytical model of residual stress is proposed considering the effects of CO. The hybrid McDowell algorithm is used to predict the residual stress with the developed plastic modulus. Finally, the sensitivity analysis is carried out, with the result showing that the effect of CO on residual stress is significant.
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HANON, Guillaume. "Heterogeneity of strain and texture inside roll-bonded multilaminates". In Material Forming. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644903131-191.
Abstract (sommario):
Abstract. This study demonstrates the usefulness of crystal plasticity modeling and crystallographic texture analysis when aiming to understand through-thickness strain heterogeneity after roll bonding of dissimilar materials. FE modeling was used at two length scales to study the deformation and texture heterogeneities inside a 9-layer multilaminate made of aluminum and steel, produced by roll-bonding. Microstructure and crystallographic texture were probed using EBSD. Numerical predictions indicated that plane strain compression was accompanied by significant shear parallel to the rolling plane and inclined shear banding in aluminum. Predictions of the Texture development were more accurate in the bcc phase than the fcc phase.
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Gong, Xibing, Xiaoqing Wang, Vernon Cole, Zachary Jones, Kenneth Cooper e Kevin Chou. "Characterization of Microstructure and Mechanical Property of Inconel 718 From Selective Laser Melting". In ASME 2015 International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/msec2015-9317.
Abstract (sommario):
In this study, the microstructures and mechanical properties of Inconel 718 fabricated from selective laser melting (SLM) process were experimentally investigated. Specimens with different build heights were prepared for microstructural observations by optical microscopy and scanning electron microscope. The texture evolution was also examined using electron backscatter diffraction (EBSD). In general, columnar γ dendrites are found along the build direction from the X-plane (side surface), while the microstructure of Z-plane (scanning surface) is characterized by equiaxed grains. The microstructures vary along the build height: the top layers present coarse columnar dendrites while the bottom layers show much narrower columnar dendrites owing to a higher cooling rate. The top layers also present the combination of a γ matrix and a higher percentage of the Laves phase, while the bottom layers show a much less Laves phase due to, again, a higher cooling rate. Random textures are shown for the SLM Inconel 718 samples. Nanoindentation tests identify the Young’s modulus and hardness of about 200 GPa and 7 GPa, respectivley.
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Xiong, Zhen, Yingbin Zhang, Shaoyong Fu, Zhiqiang Zhang, Guanchao Xu, Zhiqiang Feng, Junhao Chu e Pierre J. Verlinden. "Crystal growth, microstructure characterization and cell performance analysis of casting-monocrystalline ingots with <111> orientation". In 2014 IEEE 40th Photovoltaic Specialists Conference (PVSC). IEEE, 2014. http://dx.doi.org/10.1109/pvsc.2014.6925574.
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Satoh, Gen, Y. Lawrence Yao, Xu Huang e Ainissa Ramirez. "Characterization and Prediction of Texture in Laser Annealed NiTi Shape Memory Thin Films". In ASME 2010 International Manufacturing Science and Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/msec2010-34250.
Abstract (sommario):
Thin film shape memory alloys are a promising material for use in micro-scale devices for actuation and sensing due to their strong actuating force, substantial displacements, and large surface to volume ratios. NiTi, in particular, has been of great interest due to its biocompatibility and corrosion resistance. Effort has been directed toward adjusting the microstructure of as-deposited films in order to modify their shape memory properties for specific applications. The anisotropy of the shape memory and superelastic effects suggests that inducing preferred orientations could allow for optimization of shape memory properties. Limited work, however, has been performed on adjusting the crystallographic texture of these films. In this study, thin film NiTi samples are processed using excimer laser crystallization and the effect on the overall preferred orientation is analyzed through the use of electron backscatter diffraction and x-ray diffraction. A 3-dimensional Monte Carlo grain growth model is developed to characterize textures formed through surface energy induced abnormal grain growth during solidification. Furthermore, a scaling factor between Monte Carlo steps and real time is determined to aid in the prediction of texture changes during laser crystallization in the partial melting regime.