Author: Frank Reginald Nunes Nabarro
Publisher: Elsevier Science & Technology
ISBN:
Category : Science
Languages : en
Pages : 592

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Book Description

Author: Frank R.N. Nabarro
Publisher: Elsevier
ISBN: 9780444514837
Category : Science
Languages : en
Pages : 668

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Book Description
This is the first volume to appear under the joint editorship of J.P. Hirth and F.R.N. Nabarro. While Volume 11 concentrated on the single topic of dislocations and work hardening, the present volume spreads over the whole range of the study of dislocations from the application by Kléman and his colleagues of homotopy theory to classifying the line and point defects of mesomorphic phases to Chaudhri's account of the experimental observations of dislocations formed around indentations. Chapter 64, by Cai, Bulatove, Chang, Li and Yip, discusses the influence of the structure of the core of a dislocation on its mobility. The power of modern computation allows this topic to be treated from the first principles of electron theory, and with empirical potentials for more complicated problems. Advances in electron microscopy allow these theoretical predictions to be tested. In Chapter 65, Xu analyzes the emission of dislocations from the tip of a crack and its influence on the brittle to ductile transition. Again, the treatment is predominantly theoretical, but it is consistently related to the very practical example of alpha iron. In a dazzling interplay of experiment and abstract mathematics, Kléman, Lavrentovich and Nastishin analyze the line and point structural defects of the many mesomorphic phases which have become known in recent years. Chapter 67, by Coupeau, Girard and Rabier, is essentially experimental. It shows how the various modern techniques of scanning probe microscopy can be used to study dislocations and their interaction with the free surface. Chapter 68, by Mitchell and Heuer, considers the complex dislocations that can form in ceramic crystals on the basis of observations by transmission electron microscopy and presents mechanistic models for the motion of the dislocations in various temperature regimes. While the underlying aim of the study of dislocations in energetic crystals by Armstrong and Elban in Chapter 69 is to understand the role of dislocations in the process of detonation, it has the wider interest of studying dislocations in molecular crystals which are ``elastically soft, plastically hard, and brittle''. Chaudhri in Chapter 70 discusses the role of dislocations in indentation processes, largely on the basis of the elastic analysis by E.H. Yoffe. The special case of nanoindentations is treated only briefly.

Author:
Publisher: Elsevier
ISBN: 0080472540
Category : Technology & Engineering
Languages : en
Pages : 603

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Book Description
This is the first volume to appear under the joint editorship of J.P. Hirth and F.R.N. Nabarro. While Volume 11 concentrated on the single topic of dislocations and work hardening, the present volume spreads over the whole range of the study of dislocations from the application by Kléman and his colleagues of homotopy theory to classifying the line and point defects of mesomorphic phases to Chaudhri's account of the experimental observations of dislocations formed around indentations.Chapter 64, by Cai, Bulatove, Chang, Li and Yip, discusses the influence of the structure of the core of a dislocation on its mobility. The power of modern computation allows this topic to be treated from the first principles of electron theory, and with empirical potentials for more complicated problems. Advances in electron microscopy allow these theoretical predictions to be tested.In Chapter 65, Xu analyzes the emission of dislocations from the tip of a crack and its influence on the brittle to ductile transition. Again, the treatment is predominantly theoretical, but it is consistently related to the very practical example of alpha iron.In a dazzling interplay of experiment and abstract mathematics, Kléman, Lavrentovich and Nastishin analyze the line and point structural defects of the many mesomorphic phases which have become known in recent years.Chapter 67, by Coupeau, Girard and Rabier, is essentially experimental. It shows how the various modern techniques of scanning probe microscopy can be used to study dislocations and their interaction with the free surface.Chapter 68, by Mitchell and Heuer, considers the complex dislocations that can form in ceramic crystals on the basis of observations by transmission electron microscopy and presents mechanistic models for the motion of the dislocations in various temperature regimes.While the underlying aim of the study of dislocations in energetic crystals by Armstrong and Elban in Chapter 69 is to understand the role of dislocations in the process of detonation, it has the wider interest of studying dislocations in molecular crystals which are ``elastically soft, plastically hard, and brittle''.Chaudhri in Chapter 70 discusses the role of dislocations in indentation processes, largely on the basis of the elastic analysis by E.H. Yoffe. The special case of nanoindentations is treated only briefly.

Author: G. Kostorz
Publisher: Elsevier
ISBN: 1483274926
Category : Technology & Engineering
Languages : en
Pages : 471

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Book Description
Fundamental Aspects of Dislocation Interactions: Low-Energy Dislocation Structures III covers the papers presented at a European Research Conference on Plasticity of Materials-Fundamental Aspects of Dislocation Interactions: Low-Energy Dislocation Structures III, held on August 30-September 4, 1992 in Ascona, Switzerland. The book focuses on the processes, technologies, reactions, transformations, and approaches involved in dislocation interactions. The selection first offers information on work softening and Hall-Petch hardening in extruded mechanically alloyed alloys and dynamic origin of dislocation structures in deformed solids. Discussions focus on stress-strain behavior in relation to composition, structure, and annealing; comparison of stress-strain curves with work softening theory; sweeping and trapping mechanism; and model of dipolar wall structure formation. The text then ponders on plastic instabilities and their relation to fracture and dislocation and kink dynamics in f.c.c. metals studied by mechanical spectroscopy. The book takes a look at misfit dislocation generation mechanisms in heterostructures and evolution of dislocation structure on the interfaces associated with diffusionless phase transitions. Discussions focus on dislocation representation of a wall of elastic domains; equation of equilibrium of an elastic domain; transformation of dislocations; and theoretical and experimental background. The selection is a valuable reference for readers interested in dislocation interactions.

Author: John Arthur Simmons
Publisher:
ISBN:
Category : Dislocations in crystals
Languages : en
Pages : 752

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Book Description

Author: Frank Reginald Nunes Nabarro
Publisher: North Holland
ISBN:
Category : Science
Languages : en
Pages : 588

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Book Description
It was fashionable at one time to say that, while dislocations were pleasant playthings for physicists and could explain some long-established technological observations, their study did not contribute to the advance of technology and the economy. The chapters in Volume 8 remind us that a knowledge of esoteric topics, such as interfacial dislocations and the detailed structure of the cores of dislocations in unusual crystal structures, has been essential in the development of semiconductor devices and of superalloys.

Author: Frank Reginald Nunes Nabarro
Publisher: Elsevier Science & Technology
ISBN:
Category : Science
Languages : en
Pages : 444

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Book Description
It is clear that disclination theory has not, or not yet, shown the power of physical explanation that has come from dislocation theory. However, there are many indications that its importance will grow. There is increasing interest in the structure of highly deformed metals, and their deformation obviously involves large mutual rotations of neighbouring elements. There is a strong, but not remarkably successful, activity in the theory of the formation of dislocation patterns during deformation, and these patterns are essentially disclinations. This volume contains four chapters: Chapter 44 illustrates the great advances which have occurred in the electron microscopy of dislocations, reporting on both the current theoretical position and the most accurate experimental observations. Chapter 45 gives a thorough analysis of the internal friction arising from the production and motion of kinks in dislocations lying in Peierls valleys. Chapter 46 treats another problem of dislocation dynamics, concluding that the processes are essentially different in f.c.c. and b.c.c. metals.Chapter 47 discusses a topic which has been studied more vigorously in the Soviet Union than in the West, providing a summary of experimental observations on various kinds of rotational deformation together with a comprehensive bibliography. A detailed account of the elastic theory of disclinations is also presented here in a single chapter.

Author: Roman Teisseyre
Publisher: Academic Press
ISBN: 0080530656
Category : Science
Languages : en
Pages : 697

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Book Description
A group of distinguished scientists contributes to the foundations of a new discipline in Earth sciences: earthquake thermodynamics and thermodynamics of formation of the Earth's interior structures. The predictive powers of thermodynamics are so great that those aspiring to model earthquake and the Earth's interior will certainly wish to be able to use the theory. Thermodynamics is our only method of understanding and predicting the behavior of many environmental, atmospheric, and geological processes. The need for Earth scientists to develop a functional knowledge of thermodynamic concepts and methodology is therefore urgent. Sources of an entropy increase the dissipative and self-organizing systems driving the evolution and dynamics of the Universe and Earth through irreversible processes. The non-linear interactions lead to the formation of fractal structures. From the structural phase transformations the important interior boundaries emerge.Non-linear interactions between the defects in solids lead the authors to develop the physics of continua with a dense distribution of defects. Disclinations and dislocations interact during a slow evolution as well as during rapid dynamic events, like earthquakes. Splitting the dynamic processes into the 2D fault done and 3D surrounding space brings a new tool for describing the slip nucleation and propagation along the earthquake faults. Seismic efficiency, rupture velocity, and complexity of seismic source zone are considered from different points of view, fracture band earthquake model is developed on the basis of thermodynamics of line defects, like dislocations. Earthquake thermodynamics offers us a microscopic model of earthquake sources.Physics of defects helps the authors decscribe and explain a number of precursory phenomena caused by the buildup of stresses. Anomalies in electric polarization and electromagnetic radiation prior to earthquakes are considered from this point of view. Through the thermodynamic approach, the authors arrive at the fascinating question of posssibility of earthquake prediction. In general, the Earth is considered here as a multicomponent system. Transport phenomena as well as wave propagation and shock waves are considered in this system subjected also to chemical and phase transformations.

Author: Frank Reginald Nunes Nabarro
Publisher: North Holland
ISBN:
Category : Science
Languages : en
Pages : 456

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Book Description
This volume begins with a review of a recent development, the study of the electrical noise associated with the presence and motion of dislocations and point defects during plastic deformation. The second chapter gives a detailed account of the mechanisms which resist the motion of a dislocation through the crystal lattice, a topic which is fundamental to any dynamical theory of plastic deformation. This is followed by a review of the properties of dislocations in covalent crystals which display the remarkable interaction between the mechanical and electrical properties of dislocations in semiconductors. The last two chapters are concerned with more direct applications, such as the formation and evolution of dislocation structures during radiation damage and how the role of dislocations in martenistic transformations can now be discussed in a quantitative study of the influence of dislocations on martensitic transformations.

Author: Isao Tanaka
Publisher: Springer
ISBN: 9789811677144
Category : Technology & Engineering
Languages : en
Pages : 278

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Book Description
This open access book presents the novel concept of plaston, which accounts for the high ductility or large plastic deformation of emerging high-performance structural materials, including bulk nanostructured metals, hetero-nanostructured materials, metallic glasses, intermetallics, and ceramics.The book describes simulation results of the collective atomic motion associated with plaston, by computational tools such as first-principle methods with predictive performance and large-scale atom-dynamics calculations. Multi-scale analyses with state-of-the art analytical tools nano/micro pillar deformation and nano-indentation experiments are also described. Finally, through collaborative efforts of experimental and computational work, examples of rational design and development of new structural materials are given, based on accurate understanding of deformation and fracture phenomena.This publication provides a valuable contribution to the field of structural materials research.