Download or read book Molecular Dynamics Simulations of Grain Boundary and Bulk Diffusion in Metals written by Steven James Plimpton and published by . This book was released on 1989 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Grain Boundary Migration in Metals written by Hao Zhang and published by . This book was released on 2005 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Dynamics Simulation of Grain Boundary Migration written by Jian Zhou and published by Cuvillier Verlag. This book was released on 2012-03-05 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Migration of tilt 111 grain boundaries (GBs) in aluminum has been simulated in a wide temperature range with various magnitudes of driving force. It is found that under different conditions GBs migrate through either a diffusionless or a diffusional mechanism. The essence of the diffusionless mechanism is determined to be GB dislocation glide. This mechanism agrees with many previously reported mechanisms, consisting of the collective motion of atom groups, the four-atom shuffling and the boundary motion by glide of primary/secondary GB dislocations. GB dislocation glide therefore serves as a generalized mechanism for all of them. The diffusional mechanism is merely observed to occur for high-angle GBs at high temperatures when a relatively small driving force of several MPa is applied. For these GBs featured in thick and highly disordered structures, GB migration is controlled by GB diffusion. The effects of structural constraints, temperature, GB misorientation and driving force magnitude, on the activation of either mechanism as well as on concrete GB migration behaviors are discussed. Based on these discussions, two GB migration mechanism maps for polycrystals are proposed. The mechanism maps can well explain many contradictory findings obtained previously in both experiments and simulations. In addition, GB mobilities are evaluated at a high temperature. The simulated values are physically reasonable as high-angle GBs move faster than low-angle GBs and the maximum mobility occurs around 40° misorientation. The mobility of a Σ7 GB even approaches the maximum experimental value obtained in ultra-high-purity bicrystals.

Download or read book Molecular Dynamics and Diffusion written by David J. Fisher and published by Trans Tech Publications Ltd. This book was released on 2013-04-19 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The molecular dynamics technique was developed in the 1960s as the outgrowth of attempts to model complicated systems by using either a) direct physical simulation or (following the great success of Monte Carlo methods) by b) using computer techniques. Computer simulation soon won out over clumsy physical simulation, and the ever-increasing speed and sophistication of computers has naturally made molecular dynamics simulation into a more and more successful technique. One of its most popular applications is the study of diffusion, and some experts now even claim that molecular dynamics simulation is, in the case of situations involving well-characterised elements and structures, more accurate than experimental measurement. The present double volume includes a compilation (over 600 items) of predicted solid-state diffusion data, for all of the major materials groups, dating back nearly four decades. The double volume also includes some original papers: “Determination of the Activation Energy for Formation and Migration of Thermal Vacancies in 401.0 Casting Aluminum Alloy” (N.A.Kamel et al.), “A Study of the Effect of Natural Aging on Some Plastically Deformed Aluminum Alloys using Two Different Techniques” (N.A.Kamel), “Estimation of Crystalline Size of Deformed 5251 Al Alloy using PALT and XRD Techniques” (M.A.Abdel-Rahman et al.), “Determination of the Activation Energy for Formation and Migration of Thermal Vacancies in 2024 Aircraft Material using Different Techniques and Methods” (N.A.Kamel), “Annealing Study of Al-Mg Wrought Alloys using Two Different Techniques and Estimation of the Activation Enthalpy of Migrating Defects” (G.Attallah et al.), “Studying the Formation of Fe2SiO4 and Pearlite Phases in Iron-Silica Sand Nanoparticle Composites” (T.Ahmad et al.), “Studies of Knight Shifts and Hyperfine Structure Constants of Tl2Ba2CuO6+y” (M.Q.Kuang et al.).

Download or read book Grain Boundary Migration in Metals written by Gunter Gottstein and published by CRC Press. This book was released on 2009-12-23 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major goal of materials science is to create new engineering materials and optimize their cost and performance. Understanding how adjacent materials behave at their borders is an essential part of this process. Grain boundaries are the longest-known crystal defects, but although they were discovered in the mid-eighteenth century, until quite rece

Download or read book Defects and Diffusion in Metals written by David J. Fisher and published by Trans Tech Publications Ltd. This book was released on 2000-01-05 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second issue, following DDF165-166, to cover recent progress in this field. As usual, priority in abstracting has been given to the most accessible work and, in particular, to those papers which furnish original data or report important new techniques, phenomena or anomalies, although there is also extensive overage of more qualitative features of diffusion and defect phenomena, of the predictions of computer models, and of theoretical studies.

Download or read book Defects and Diffusion in Metals 2007 written by David J. Fisher and published by Trans Tech Publications Ltd. This book was released on 2007-05-15 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Defect and Diffusion Forum Vol. 265

Download or read book Grain Boundary Migration in Metals written by Gunter Gottstein and published by CRC Press. This book was released on 2009-12-23 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major goal of materials science is to create new engineering materials and optimize their cost and performance. Understanding how adjacent materials behave at their borders is an essential part of this process. Grain boundaries are the longest-known crystal defects, but although they were discovered in the mid-eighteenth century, until quite rece

Download or read book Determination of Vacancy Mechanism for Grain Boundary Self diffusion by Computer Simulation written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It is currently well established that the fast self-diffusion which occurs along grain boundaries (GBs) in metals must occur by a point defect exchange mechanism. For example, it is known that rapid GB diffusion can transport a net current of atoms along GBs during both sintering and diffusional creep, and that the two species in a binary substitutional alloy diffuse at different rates in GBs. However, it has not been possible to establish firmly whether the defect mechanism involves the exchange of atoms with vacancy or interstitial point defects. It has been suspected that the vacancy exchange mechanism must apply but it has been difficult to prove this hypothesis because of a lack of detailed information at the atomistic level. The results are presented of an effort to establish the GB self-diffusion mechanism in a bcc iron .sigma. = 5 (36.9°) (001) (310) tilt boundary using the combined methods of computer molecular statics and molecular dynamics simulation.

Download or read book Mass Transport in Solids written by F. Bénière and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomic transport in solids is a field of growing importance in solid state physics and chemistry, and one which, moreover, has important implications in several areas of materials science. This growth is due first to an increase in the understanding of the fund amentals of transport processes in solids. Of equal importance, however, have been the improvements in the last decade in the experi mental techniques available for the investigation of transport phenomena. The advances in technique have stimulated studies of a wider range of materials; and expansion of the field has been strong ly encouraged by the increasing range of applied areas where transport processes play an essential role. For example, mass transport phenomena play a critical role in the technology of fabrication of components in the electronics industry. Transport processes are involved both during the fabrication and operation of devices and with the growing trend to miniaturisation there are increasing demands on accurate control of diffusion processes. The present book (which is based on a NATO sponsored Advanced Study Institute held in 1981 at Lannion, France) aims to present a general survey of the subject, highlighting those areas where work has been especially active in recent years.

Download or read book Grain Boundary Diffusion and Grain Boundary Segregation written by B. Bokstein and published by . This book was released on 1998 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomena of grain boundary diffusion and grain boundary segregation play major roles in determining the properties and behavior of a wide variety of materials. Even though the basic principles have been known for a long time, the field continues to yield a number of very challenging questions.

Download or read book Diffusion Processes in Advanced Technological Materials written by Devendra Gupta and published by Springer Science & Business Media. This book was released on 2013-01-15 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new game book for understanding atoms at play aims to document diffusion processes and various other properties operative in advanced technological materials. Diffusion in functional organic chemicals, polymers, granular materials, complex oxides, metallic glasses, and quasi-crystals among other advanced materials is a highly interactive and synergic phenomenon. A large variety of atomic arrangements are possible. Each arrangement affects the performance of these advanced, polycrystalline multiphase materials used in photonics, MEMS, electronics, and other applications of current and developing interest. This book is written by pioneers in industry and academia for engineers, chemists, and physicists in industry and academia at the forefront of today's challenges in nanotechnology, surface science, materials science, and semiconductors.

Download or read book Grain Boundary Diffusion Stresses and Segregation written by Boris S. Bokstein and published by Trans Tech Publications Ltd. This book was released on 2011-03-15 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special collection concentrates on three basic topics, the 35 peer-reviewed papers being grouped into: 1. Grain Boundary Diffusion, Segregation and Stresses, 2. Bulk Diffusion and Phase Formation and 3. Diffusion-Controlled Processes. It provides succinct and timely coverage of these topics. Volume is indexed by Thomson Reuters CPCI-S (WoS).

Download or read book Computer Simulation Studies of Grain Boundary Systems and Molecular Solids written by Sidney Yip and published by . This book was released on 1983 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural, thermodynamic and mechanical properties of bicrystals have been studied using molecular dynamics and Monte Carlo simulation. A grain boundary melting transition in a two-dimensional system has been observed. Atomic diffusion along grain boundaries was investigated by following in detail the migration of a vacancy initially introduced into the bicrystal. The activation energy for vacancy migration in iron has been determined, and thermal activation of Frenkel pairs in the grain boundary core was observed. Structural phase transformation in stressed solids has been studied using an extended Monte Carlo method. Stress-strain relations obtained for iron showed the existence of bcc - fcc transition under tension or compression. Dynamical properties of a one-dimensional nonlinear lattice (the U4-lattice) have been analyzed in terms of kink propagation and damping and kink diffusion. Both perturbation theory and molecular dynamic calculations were carried out. (Author).

Download or read book Molecular Dynamics Study of Grain Boundary Structure and Properties at High Temperatures written by Saryu Jindal Fensin and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports research involving the development and application of atomistic simulation methods to study the effects of high homologous temperatures on the structural, thermodynamic, kinetic and mechanical properties of grain boundaries in metals. In this work we study two different elemental systems, namely Ni and Cu, and consider a variety of grain boundary structures characterized by different misorientation angles, twist/tilt character and zero-temperature energies. A method to calculate the disjoining potential from molecular dynamics is developed and applied to grain boundaries in Ni. The disjoining potential characterizes the variation in grain-boundary free energy as a function of the width of a premelted interfacial layer. The MD method for the calculation of this property is applied to grain boundaries that display continuous premelting transitions, as well as a boundary characterized by a disordered atomic structure displaying a finite interfacial width at the melting temperature. We also develop analysis methods to characterize the change in the atomic structure of an asymmetric tilt grain boundary in elemental Cu as a function of temperature. This boundary is characterized by a potential-energy surface with multiple minima as a function of the relative translation of the grains parallel to the interface plane. The structure of this boundary is found to display both disordering and roughening with increasing temperature. The mobility was calculated at high homologous temperatures using a method based on the analysis of the random walk of the interface in equilibrium MD simulations. Finally, the temperature dependent response of this grain boundary to shear was investigated. The dynamical behavior of the boundary in response to an applied shear strain was observed to undergo qualitative changes as the temperature was increased above 700 K.A decrease in shear resistance of the grain boundaries as a function of temperature was characterized by a decrease in the critical shear stress, an upper bound for which was estimated to be roughly a factor of five lower at the melting temperature than at zero temperature.

Download or read book Defects and Diffusion in Metals written by and published by . This book was released on 2002 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Grain Boundary Segregation in Metals written by Pavel Lejcek and published by Springer Science & Business Media. This book was released on 2010-07-20 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.