Download or read book Molecular Dynamics Study of Microstructural Evolution in Alloys Subjected to Severe Plastic Deformation written by Samson Olusikunanu Odunuga and published by ProQuest. This book was released on 2007 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The atomic transport resulting from plastic deformation has been analyzed in new depths by tracking the evolution of pair of marker atoms. This analysis has proved to be a powerful tool in identifying the deformation mechanisms, including the glide of leading and trailing partial dislocations, and vacancy assisted atomic jumps during deformation, as well as quantifying the relative contributions of these mechanisms. It is found that the glide of dislocations plays a more important role than previously thought in accommodating plastic deformation in nanocrystalline alloys. A new property of the atomic mixing by plastic deformation that has been uncovered is that the effective diffusion coefficient increases, nearly linearly, with the separation distance of pairs of atoms. This superdiffusive mixing is revealed by monitoring the relative displacement of atoms as a function of the separation distance. This result can be tested experimentally by measuring the rate of dissolution of precipitates during deformation. This finding also provides a direct rationalization for the stabilization of compositional patterns when thermal diffusion and forced mixing compete.

Download or read book Multi scale Modeling of Microstructural Evolution in Structural Metallic Systems written by Lei Zhao and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic alloys are a widely used class of structural materials, and the mechanical properties of these alloys are strongly dependent on the microstructure. Therefore, the scientific design of metallic materials with superior mechanical properties requires the understanding of the microstructural evolution. Computational models and simulations offer a number of advantages over experimental techniques in the prediction of microstructural evolution, because they can allow studies of microstructural evolution in situ, i.e., while the material is mechanically loaded (meso-scale simulations), and bring atomic-level insights into the microstructure (atomistic simulations). In this thesis, we applied a multi-scale modeling approach to study the microstructural evolution in several metallic systems, including polycrystalline materials and metallic glasses (MGs). Specifically, for polycrystalline materials, we developed a coupled finite element model that combines phase field method and crystal plasticity theory to study the plasticity effect on grain boundary (GB) migration. Our model is not only coupled strongly (i.e., we include plastic driving force on GB migration directly) and concurrently (i.e., coupled equations are solved simultaneously), but also it qualitatively captures such phenomena as the dislocation absorption by mobile GBs. The developed model provides a tool to study the microstructural evolution in plastically deformed metals and alloys. For MGs, we used molecular dynamics (MD) simulations to investigate the nucleation kinetics in the primary crystallization in Al-Sm system. We calculated the time-temperature-transformation curves for low Sm concentrations, from which the strong suppressing effect of Sm solute on Al nucleation and its influencing mechanism are revealed. Also, through the comparative analysis of both Al attachment and Al diffusion in MGs, it has been found that the nucleation kinetics is controlled by interfacial attachment of Al, and that the attachment behavior takes place collectively and heterogeneously, similarly to Al diffusion in MGs. Finally, we applied the MD technique to study the origin of five-fold twinning nucleation during the solidification of Al base alloys. We studied several model alloys and reported the observed nucleation pathway. We found that the key factors controlling the five-fold twinning are the twin boundary energy and the formation of pentagon structures, and the twin boundary energy plays the dominant role in the five-fold twinning in the model alloys studied.

Download or read book Severe Plastic Deformation Techniques written by Marcello Cabibbo and published by BoD – Books on Demand. This book was released on 2017-08-09 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grain size is recognized as a key microstructural factor affecting mechanical and, to some extent, physical properties of metals and metallic materials. For this reason, all the means designed to control and modify the grain size are considered a proper way to design and tailor metallic materials with desired properties. In this sense, microstructure refinement through severe plastic deformation (SPD) techniques can be considered a key method for this purpose. A typical SPD process is currently defined as any method of metal forming under extensive hydrostatic pressure intended to impose a very high strain on a bulk solid without involving any significant change in the overall dimensions and having the ability to produce exceptional grain refinement. What makes SPD processing techniques so popular and attractive is the possibility of using them to enhance the strength behavior of conventional metallic materials by a factor of up to eight for pure metals such as copper and by some 30-50% for alloys. Despite the impressive property improvement achievable with SPD techniques, their uptake by industry has been rather sluggish. This book intends to give a panorama of the typical SPD techniques intended to optimize the mechanical and physical properties of metals through a significant grain size reduction process. Modeling for this purpose is also presented.

Download or read book Severe Plastic Deformation and Thermomechanical Processing Nanostructuring and Properties written by Andrea Bachmaier and published by MDPI. This book was released on 2021-02-11 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Severe plastic deformation (SPD) is a very attractive research field for metallic materials because it provides new possibilities for manufacturing nanostructured materials in large quantities and allows microstructural design on different hierarchical levels. The papers included in this issue address the following topics: novel SPD processes as well as recent advancements in established processing methods, microstructure evolution and grain refinement in single- and multi-phase alloys as well as composites, strategies to enhance the microstructure stability at elevated temperatures, mechanically driven phase transformations, surface nanostructuring, gradient and multilayered materials, and mechanical and physical properties of SPD-processed materials.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermo Mechanically Coupled Cyclic Deformation and Fatigue Failure of NiTi Shape Memory Alloys written by Guozheng Kang and published by Springer Nature. This book was released on 2023-07-24 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by leading experts in the field, this book highlights an authoritative and comprehensive introduction to thermo-mechanically coupled cyclic deformation and fatigue failure of shape memory alloys. The book deals with: (1) experimental observations on the cyclic deformation and fatigue failure in the macroscopic and microscopic scales; (2) molecular dynamics and phase-field simulations for the thermo-mechanical behaviors and underlying mechanisms during cyclic deformation; (3) macroscopic phenomenological and crystal plasticity-based cyclic constitutive models; and (4) fatigue failure models. This book is an important reference for students, practicing engineers and researchers who study shape memory alloys in the areas of mechanical, civil and aerospace engineering as well as materials science.

Download or read book Nanomaterials by Severe Plastic Deformation written by Michael J. Zehetbauer and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings of the "Second International Conference on Nanomaterials by Severe Plastic Deformation" review the enormous scientific avalanche that has been developing in the field over recent years. A valuable resource for any scientist and engineer working in this emerging field of nanotechnology.

Download or read book Microstructure Prediction of Severe Plastic Deformation Manufacturing Processes for Metals written by Ninggang Shen and published by . This book was released on 2018 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the research presented in this thesis has been to develop a physics-based dislocation density-based numerical framework to simulate microstructure evolution in severe plastic deformation (SPD) manufacturing processes for different materials. Different mechanisms of microstructure evolution in SPD manufacturing processes were investigated and summarized for different materials under dynamic or high strain rates over a wide temperature range. Thorough literature reviews were performed to clarify discrepancies of the mechanism responsible for the formation of nanocrystalline structure in the machined surface layer under both low-temperature and high-temperature conditions. Under this framework, metallo-thermo-mechanically (MTM) coupled finite element (FE) models were developed to predict the microstructure evolution during different SPD manufacturing processes. Different material flow stress responses were modeled subject to responsible plastic deformation mechanisms. These MTM coupled FE models successfully captured the microstructure evolution process for various materials subjected to multiple mechanisms. Cellular automaton models were developed for SPD manufacturing processes under intermediate to high strain rates for the first time to simulate the microstructure evolution subjected to discontinuous dynamic recrystallization and thermally driven grain growth. The cellular automaton simulations revealed that the recrystallization process usually cannot be completed by the end of the plastic deformation under intermediate to high strain rates. The completion of the recrystallization process during the cooling stage after the plastic deformation process was modeled for the first time for SPD manufacturing processes at elevated temperatures.

Download or read book Magnesium Alloys and Their Applications written by Barry L. Mordike and published by . This book was released on 1998 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Severe Plastic Deformation of Difficult to work Alloys written by Guney Guven Yapici and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work aims to reveal the microstructural evolution and post-processing mechanical behavior of difficult-to-work alloys upon severe plastic deformation. Severe plastic deformation is applied using equal channel angular extrusion (ECAE) where billets are pressed through a 90° corner die achieving simple shear deformation. Three different materials are studied in this research, namely Ti-6Al-4V, Ti-6Al-4V reinforced with 10% TiC and AISI 316L stainless steel. Microstructure and mechanical properties of successfully extruded billets were reported using light microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), tension and compression experiments and microhardness measurements. The effects of extrusion conditions (temperature and processing route) on the microstructure and mechanical properties are investigated. The underlying mechanisms responsible for observed mechanical behaviors are explored. It is seen that ECAE shear deformation leads to refinement in ł plates and elimination of prior [beta] boundaries in Ti-6Al-4V. Decreasing extrusion temperature and increasing number of passes decreases [alpha] plate size and grain size. Refined [alpha] grain size leads to a significant increase in tensile and compressive flow stresses at room temperature. Texture produced by ECAE has a pronounced effect on mechanical properties. Specifically it leads to tension/compression asymmetry in flow strengths and strain hardening coefficients may be described by the activation of differing slip systems under tension and compression loading. ECAE of Ti-6Al-4V+10%TiC samples also improved mechanical properties due to ł plate size refinement. Nevertheless, further extrusion passes should be carried out for tailoring reinforcement size and distribution providing optimum strength and ductility. ECAE deformation of AISI 316L stainless steel at high homologous temperatures (0.55 to 0.60 T[subscript]m) results in deformation twinning as an effective deformation mechanism which is attributed to the effect of the high stress levels on the partial dislocation separation. Deformation twinning gives rise to high stress levels during post-processing room temperature tension and compression experiments by providing additional barriers to dislocation motion and decreasing the mean free path of dislocations. The highest tensile flow stress observed in the sample processed at 700°C following one pass route A was on the order of 1200 MPa which is very high for 316L stainless steel. The ultimate goal of this study is to produce stabilized end microstructures with improved mechanical properties and demonstrate the applicability of ECAE on difficult-to-work alloys.

Download or read book Nanostructured Metals and Alloys written by S H Whang and published by Elsevier. This book was released on 2011-03-22 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tensile strength, fatigue strength and ductility are important properties of nanostructured metallic materials, which make them suitable for use in applications where strength or strength-to-weight ratios are important. Nanostructured metals and alloys reviews the latest technologies used for production of these materials, as well as recent advances in research into their structure and mechanical properties.One of the most important issues facing nanostructured metals and alloys is how to produce them. Part one describes the different methods used to process bulk nanostructured metals and alloys, including chapters on severe plastic deformation, mechanical alloying and electrodeposition among others. Part two concentrates on the microstructure and properties of nanostructured metals, with chapters studying deformation structures such as twins, microstructure of ferrous alloys by equal channel angular processing, and characteristic structures of nanostructured metals prepared by plastic deformation. In part three, the mechanical properties of nanostructured metals and alloys are discussed, with chapters on such topics as strengthening mechanisms, nanostructured metals based on molecular dynamics computer simulations, and surface deformation. Part four focuses on existing and developing applications of nanostructured metals and alloys, covering topics such as nanostructured steel for automotives, steel sheet and nanostructured coatings by spraying.With its distinguished editor and international team of contributors, Nanostructured metals and alloys is a standard reference for manufacturers of metal components, as well as those with an academic research interest in metals and materials with enhanced properties.

Download or read book Reactive Sputter Deposition written by Diederik Depla and published by Springer Science & Business Media. This book was released on 2008-06-24 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

Download or read book Trends in Plasticity of Metals and Alloys written by Mikha]ıl A Lebyodkin and published by . This book was released on 2021-10-21 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last few decades have seen considerable progress in the development of high-performance metals and alloys that have microstructures and plastic behaviors with a high level of complexity. Ultrafine-grain materials, metallic glasses, gradient microstructures, etc., have clearly been gaining the attention of researchers and are gaining a place in the industry. Concurrently, the self-organized nature of plastic deformation, leading to complex behaviors on mesoscopic scales even in pure metals with highly symmetric lattices, has been generally recognized. Such progress has demanded the development of sophisticated experimental techniques (in situ TEM, digital image correlation, nano-indentation, etc.), advanced multiscale modeling (molecular dynamics, discrete dislocation dynamics, strain gradient models, etc.), and methods of analysis of the observed and simulated behaviors from the viewpoint of self-organization, with an aim of filling gaps between the elementary atomic-scale mechanisms and the scale of a laboratory sample. The current research has evolved in two main areas. First, new approaches to old questions and traditional model materials allow for a deeper understanding of physical mechanisms. Second, a better understanding of the process-microstructure-property links provides a basis for the elaboration of new materials and processing routes, as well as for the creation of powerful computer models that are able to predict the behavior of complex materials. This Special Issue aims at presenting examples of such recent progress and trends in the plasticity of metals and alloys.

Download or read book Fabrication of Gradient Microstructure Via Severe Plastic Deformation to Enhance Mechanical Performance of Metals written by Maryam Jamalian and published by . This book was released on 2020 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a high demand for low density and high strength materials to substitute heavy alloys that are currently used in the industry. The efficient solution to address this requirement is modifying the mechanical performance of available alloys via tailoring their microstructures. Gradient microstructure has exceptional potential to modify the properties of the materials without sacrificing other parameters. Mechanical incompatibility between different layers in this structure leads to extra strengthening and toughening mechanisms. Microstructural variation along the depth of thickness can be achieved via exerting desirable severe plastic deformation during the manufacturing and finishing process. The aim of this work is to develop gradient microstructure, with various statistical distributions of grain size, grain orientations, dislocation, and twins to optimize strength and ductility. To this end, several processing techniques are represented to apply static and dynamic severe plastic deformation such as high-pressure torsion (HPT) and severe shot peening (SSP). Then, the effect of various parameters in these procedures and on the creation of new microstructure such as twins, ultra-fine grains, SSD, and GND dislocation through the thickness was investigated precisely by utilizing electron backscatter diffraction (EBSD) data. Next, the role of these introduced defects and UFG grains in local hardness and overall tensile behavior was determined experimentally to establish a relationship between the microstructure and the hardening mechanism. On the other hand, subsequent annealing of heavily cold deformed structure contributes to grain boundaries modification, dislocation rearrangement or annihilation, and consequently, ductility enhancement due. Furthermore, the structure would be unstable at the thermal condition with regards to incomplete recrystallization, high density of dislocation, and smaller grain size. Thus, microstructural evolution and thermal stability of created gradient microstructure are required attention during the thermal condition.In the end, new surface treatment ``severe impact loading'' is introduced to overcome problems observed in the previous ones. In this process, the residual strain is created by a single impact wherein tensile twins formed without excessive grain refinement led to strength enhancement along with acceptable ductility.

Download or read book Thermodynamics Microstructures and Plasticity written by Alphonse Finel and published by Springer. This book was released on 2003-08-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive assessment of the various theoretical and numerical methods currently in use to investigate microstructural transformations and mechanical properties of inhomogeneous systems, from the atomic scale to the macroscopic: kinetic mean-field theories, Monte Carlo and molecular dynamics simulations, Ginzburg-Landau and phase field methods as applied to plasticity and microstructure transformation, discrete and stochastic dislocation dynamics, and cluster dynamics. Extensive surveys of major physical processes include: solidification, microstructural evolution in single and polycrystalline systems under internal and applied stress, high temperature plasticity, recrystallization, large plastic strain in multiphase systems, fatigue, fracture, diffusive transformations, and fine grained materials.

Download or read book Severe Plastic Deformation and Thermomechanical Processing Nanostructuring and Properties written by Julia Ivanisenko and published by . This book was released on 2021 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Severe plastic deformation (SPD) is a very attractive research field for metallic materials because it provides new possibilities for manufacturing nanostructured materials in large quantities and allows microstructural design on different hierarchical levels. The papers included in this issue address the following topics: novel SPD processes as well as recent advancements in established processing methods, microstructure evolution and grain refinement in single- and multi-phase alloys as well as composites, strategies to enhance the microstructure stability at elevated temperatures, mechanically driven phase transformations, surface nanostructuring, gradient and multilayered materials, and mechanical and physical properties of SPD-processed materials.

Download or read book Investigations and Applications of Severe Plastic Deformation written by Terry C. Lowe and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Material processing techniques that employ severe plastic deformation have evolved over the past decade, producing metals, alloys and composites having extraordinary properties. Variants of SPD methods are now capable of creating monolithic materials with submicron and nanocrystalline grain sizes. The resulting novel properties of these materials has led to a growing scientific and commercial interest in them. They offer the promise of bulk nanocrystalline materials for structural; applications, including nanocomposites of lightweight alloys with unprecedented strength. These materials may also enable the use of alternative metal shaping processes, such as high strain rate superplastic forming. Prospective applications for medical, automotive, aerospace and other industries are already under development.