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Languages : en
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High-purity aluminum (99.99 pct) was processed by equal-channel angular pressing (ECAP) at room temperature through a die with a 90 deg angle between the die channels. Samples were examined by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM) methods after one, four, and 12 passes through the die. Repetitively pressed samples were rotated by 90 deg in the same sense between successive pressing operations (route Bc). After one pressing, TEM showed a subgrain structure which was elongated in the shearing direction. Corresponding OIM data illustrated an inhomogeneous microstructure in which bandlike features were also aligned with the shearing direction. The lattice orientation varied from location to location in the material. The boundary disorientation distribution determined from the OIM data exhibited a peak at 2 to 5 deg, in agreement with a predominance of subgrains in the microstructure. After four pressings, the microstructure data obtained by TEM and OIM were mutually consistent. The disorientation data revealed a decrease in the population of 2 to 5 deg boundaries accompanied by an overall upward shift in the distribution. Two orientations were generally apparent in the texture, although specific orientations varied with location. Often, a (111) orientation tended to align with the shear direction. Following 12 ECA passes, the grain size was reduced further to about 1.0 mum. The populations of high-angle boundaries (greater than l5 deg) increased in the disorientation distribution. A texture characteristic of shear deformation of fcc metals became apparent, although the orientations and particular components varied with location. Microstructural refinement during severe straining includes the development of large fractions of high-angle boundaries.
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Languages : en
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Book Description
High-purity aluminum (99.99 pct) was processed by equal-channel angular pressing (ECAP) at room temperature through a die with a 90 deg angle between the die channels. Samples were examined by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM) methods after one, four, and 12 passes through the die. Repetitively pressed samples were rotated by 90 deg in the same sense between successive pressing operations (route Bc). After one pressing, TEM showed a subgrain structure which was elongated in the shearing direction. Corresponding OIM data illustrated an inhomogeneous microstructure in which bandlike features were also aligned with the shearing direction. The lattice orientation varied from location to location in the material. The boundary disorientation distribution determined from the OIM data exhibited a peak at 2 to 5 deg, in agreement with a predominance of subgrains in the microstructure. After four pressings, the microstructure data obtained by TEM and OIM were mutually consistent. The disorientation data revealed a decrease in the population of 2 to 5 deg boundaries accompanied by an overall upward shift in the distribution. Two orientations were generally apparent in the texture, although specific orientations varied with location. Often, a (111) orientation tended to align with the shear direction. Following 12 ECA passes, the grain size was reduced further to about 1.0 mum. The populations of high-angle boundaries (greater than l5 deg) increased in the disorientation distribution. A texture characteristic of shear deformation of fcc metals became apparent, although the orientations and particular components varied with location. Microstructural refinement during severe straining includes the development of large fractions of high-angle boundaries.
Author: Alexander P. Zhilyaev
Publisher: Academic Press
ISBN: 0128190779
Category : Science
Languages : en
Pages : 438
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Book Description
Superplasticity and Grain Boundaries in Ultrafine-Grained Materials, Second Edition, provides cutting-edge modeling solutions surrounding the role of grain boundaries in processes such as grain boundary diffusion, relaxation and grain growth. In addition, the book's authors explore the formation and evolution of the microstructure, texture and ensembles of grain boundaries in materials produced by severe plastic deformation. This updated edition, written by leading experts in the field, has been revised to include new chapters on the basics of nanostructure processing, the influence of deformation mechanisms on grain refinement, processing techniques for ultrafine-grained and nanostructured materials, and much more. - Provides practical applications and methods for the proper implementation of models, allowing for more effective complex metal forming processes - Features new chapters on the microstructure, mechanical behavior and functional properties of HCP metals, processing ultrafine-grained and nanostructured materials, and more - Covers experimental assessment and computational modeling techniques for adiabatic heating and saturation of grain refinement during SPD of metals and alloys
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Category :
Languages : en
Pages : 11
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Book Description
High-purity (99.99%) aluminum that had been subjected to equal-channel angular pressing (ECAP) was analyzed by orientation imaging microscopy (OIM). The analysis of microtexture and microstructure by OIM will be reviewed. The ECAP pressing was conducted at room temperature with a die that had a 900 angle between the die channels and repetitive pressings followed either route A, Bc or C. Billets were examined after one pass and after four or twelve passes by each of the ECAP routes. After one pressing operation, the deformation-induced microstructure was inhomogeneous at the resolution of OIM and consisted mostly of subgrains. Following four pressings by each of the routes, the microstructures were homogeneous and exhibited similar (sub)grain sizes l.3mum). Elongation and alignment of the (sub)grains with the shearing direction of the last pressing operation was observed in all cases. The corresponding disorientation distributions showed significant increases in the fractions of high-angle boundaries (theta greater than l5 deg) although processing route had little apparent effect on the observed distributions. However, distinct differences were noted in the microtexture data. After 12 pressing operations by any of the different routes the grain size was reduced further to about 10mum. The fraction of high-angle boundaries also increased slightly but, again, processing route had little effect on the disorientation distribution. Different textures were apparent for each processing route, although texture data for all routes indicated that a 111 tended to align with the shear plane of the final pressing pass.
Author: Paul S. Follansbee
Publisher: John Wiley & Sons
ISBN: 1118413415
Category : Technology & Engineering
Languages : en
Pages : 518
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Book Description
Offers data, examples, and applications supporting the use of the mechanical threshold stress (MTS) model Written by Paul S. Follansbee, an international authority in the field, this book explores the underlying theory, mechanistic basis, and implementation of the mechanical threshold stress (MTS) model. Readers are introduced to such key topics as mechanical testing, crystal structure, thermodynamics, dislocation motion, dislocation–obstacle interactions, hardening through dislocation accumulation, and deformation kinetics. The models described in this book support the emerging theme of Integrated Computational Materials Engineering (ICME) by offering a foundation for the bridge between length scales characterizing the mesoscale (mechanistic) and the macroscopic. Fundamentals of Strength begins with a chapter that introduces various approaches to measuring the strength of metals. Next, it covers: Structure and bonding Contributions to strength Dislocation–obstacle interactions Constitutive law for metal deformation Further MTS model developments Data analysis: deriving MTS model parameters The next group of chapters examines the application of the MTS model to copper and nickel, BCC metals and alloys, HCP metals and alloys, austenitic stainless steels, and heavily deformed metals. The final chapter offers suggestions for the continued development and application of the MTS model. To help readers fully understand the application of the MTS model, the author presents two fictional materials along with extensive data sets. In addition, end-of-chapter exercises give readers the opportunity to apply the models themselves using a variety of data sets. Appropriate for both students and materials researchers, Fundamentals of Strength goes beyond theory, offering readers a model that is fully supported with examples and applications.
Author: Yuntian Theodore Zhu
Publisher: John Wiley & Sons
ISBN: 1118804481
Category : Technology & Engineering
Languages : en
Pages : 886
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Book Description
Proceedings of a symposium sponsored by the Shaping and Forming Committee of the Materials Processing and Manufacturing Division (MPMD) and the Mechanical Behavior Committee (Jt. SMD/ASM-MSCTS) of the Structural Materials Division (SMD) of TMS (The Minerals, Metals & Materials Society) and held during the 2002 TMS Annual Meeting in Seattle, Washington February 17-21,2002.
Author: Zhe Jin
Publisher: TMS Publishing Company
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 576
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Book Description
"This is the proceedings of the third symposium on Hot Deformation in Aluminum Alloys, held in San Diego, CA, March 3-6, 2003."--p. xi.
Author: J Gubicza
Publisher: Elsevier
ISBN: 0857096141
Category : Technology & Engineering
Languages : en
Pages : 389
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Book Description
Nanomaterials exhibit unique mechanical and physical properties compared to their coarse-grained counterparts, and are consequently a major focus of current scientific research. Defect structure in nanomaterials provides a detailed overview of the processing methods, defect structure and defect-related mechanical and physical properties of a wide range of nanomaterials. The book begins with a review of the production methods of nanomaterials, including severe plastic deformation, powder metallurgy and electrodeposition. The lattice defect structures formed during the synthesis of nanomaterials are characterised in detail. Special attention is paid to the lattice defects in low stacking fault energy nanomaterials and metal – carbon nanotube composites. Topics covered in the second part of the book include a discussion of the thermal stability of defect structure in nanomaterials and a study of the influence of lattice defects on mechanical and hydrogen storage properties. - Gives in-depth, physically based explanations for the relationships between the defect structure and mechanical properties of nanomaterials - Covers a wide range of nanomaterials including metals; alloys; ceramics; diamond; carbon nanotubes and their composites - Provides a detailed characterization of the lattice defect structure in nanomaterials
Author: J Gubicza
Publisher: Woodhead Publishing
ISBN: 0081019181
Category : Technology & Engineering
Languages : en
Pages : 412
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Book Description
Defect Structure and Properties of Nanomaterials: Second and Extended Edition covers a wide range of nanomaterials including metals, alloys, ceramics, diamond, carbon nanotubes, and their composites. This new edition is fully revised and updated, covering important advances that have taken place in recent years. Nanostructured materials exhibit unique mechanical and physical properties compared with their coarse-grained counterparts, therefore these materials are currently a major focus in materials science. The production methods of nanomaterials affect the lattice defect structure (vacancies, dislocations, disclinations, stacking faults, twins, and grain boundaries) that has a major influence on their mechanical and physical properties. In this book, the production routes of nanomaterials are described in detail, and the relationships between the processing conditions and the resultant defect structure, as well as the defect-related properties (e.g. mechanical behavior, electrical resistance, diffusion, corrosion resistance, thermal stability, hydrogen storage capability, etc.) are reviewed. In particular, new processing methods of nanomaterials are described in the chapter dealing with the manufacturing procedures of nanostructured materials. New chapters on (i) the experimental methods for the study of lattice defects, (ii) the defect structure in nanodisperse particles, and (iii) the influence of lattice defects on electrical, corrosion, and diffusion properties are included, to further enhance what has become a leading reference for engineering, physics, and materials science audiences. - Provides a detailed overview of processing methods, defect structure, and defect-related mechanical and physical properties of nanomaterials - Covers a wide range of nanomaterials including metals, alloys, ceramics, diamond, carbon nanotubes, and their composites - Includes new chapters covering recent advances in both processing techniques and methods for the study of lattice defects - Provides valuable information that will help materials scientists and engineers highlight lattice defects and the related mechanical and physical properties
Author: Paul Follansbee
Publisher: Springer Nature
ISBN: 3031045564
Category : Technology & Engineering
Languages : en
Pages : 546
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Book Description
This second edition updates and expands on the class-tested first edition text, augmenting discussion of dynamic strain aging and austenitic stainless steels and adding a section on analysis of nickel-base superalloys that shows how the mechanical threshold stress (MTS) model, an internal state variable constitutive formulation, can be used to de-convolute synergistic effects. The new edition retains a clear and rigorous presentation of the theory, mechanistic basis, and application of the MTS model. Students are introduced to critical competencies such as crystal structure, dislocations, thermodynamics of slip, dislocation–obstacle interactions, deformation kinetics, and hardening through dislocation accumulation. The model described in this volume facilitates readers’ understanding of integrated computational materials engineering (ICME), presenting context for the transition between length scales characterizing the mesoscale (mechanistic) and the macroscopic. Presenting readers a model buttressed by detailed examples and applications, the textbook is ideal for students, practitioners, and materials researchers.
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Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 386
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