*Vasily V Bulatov and Wei Cai*

- Published in print:
- 2006
- Published Online:
- November 2020
- ISBN:
- 9780198526148
- eISBN:
- 9780191916618
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198526148.003.0004
- Subject:
- Computer Science, Software Engineering

Dislocations first appeared as an abstract mathematical concept. In the late 19th century, Italian mathematician Vito Volterra examined mathematical properties of singularities produced by cutting ...
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Dislocations first appeared as an abstract mathematical concept. In the late 19th century, Italian mathematician Vito Volterra examined mathematical properties of singularities produced by cutting and shifting matter in a continuous solid body [1]. As happened to some other mathematical concepts, dislocations could have remained a curious product of mathematical imagination known only to a handful of devoted mathematicians. In 1934, however, three scientists, Taylor, Polanyi and Orowan, independently proposed that dislocations may be responsible for a crystal’s ability to deform plastically [2, 3, 4]. While successfully explaining most of the puzzling phenomenology of crystal plasticity, crystal dislocations still remained mostly a beautiful hypothesis until the late 1950s when first sightings of them were reported in transmission electron microscopy (TEM) experiments [5]. Since then, the ubiquity and importance of dislocations for crystal plasticity and numerous other aspects of material behavior have been regarded as firmly established as, say, the role of DNA in promulgating life. Dislocations define a great many properties of crystalline materials. In addition to a crystal’s ability to yield and flow under stress, dislocations also control other mechanical behaviors such as creep and fatigue, ductility and brittleness, indentation hardness and friction. Furthermore, dislocations affect how a crystal grows from solution, how a nuclear reactor wall material is damaged by radiation, and whether or not a semiconductor chip in an electronic device will function properly. It can take an entire book just to describe the various roles dislocations play in materials behavior. However, the focus of this book is on the various computational models that have been developed to study dislocations. This chapter is an introduction to the basics of dislocations, setting the stage for subsequent discussions of computational models and associated numerical issues. Like any other crystal defect, dislocations are best defined with respect to the host crystal structure. We begin our discussion by presenting in Section 1.1 the basic elements and common terminology used to describe perfect crystal structures. Section 1.2 introduces the dislocation as a defect in the crystal lattice and discusses some of its essential properties. Section 1.3 discusses forces on dislocations and atomistic mechanisms for dislocation motion.
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Dislocations first appeared as an abstract mathematical concept. In the late 19th century, Italian mathematician Vito Volterra examined mathematical properties of singularities produced by cutting and shifting matter in a continuous solid body [1]. As happened to some other mathematical concepts, dislocations could have remained a curious product of mathematical imagination known only to a handful of devoted mathematicians. In 1934, however, three scientists, Taylor, Polanyi and Orowan, independently proposed that dislocations may be responsible for a crystal’s ability to deform plastically [2, 3, 4]. While successfully explaining most of the puzzling phenomenology of crystal plasticity, crystal dislocations still remained mostly a beautiful hypothesis until the late 1950s when first sightings of them were reported in transmission electron microscopy (TEM) experiments [5]. Since then, the ubiquity and importance of dislocations for crystal plasticity and numerous other aspects of material behavior have been regarded as firmly established as, say, the role of DNA in promulgating life. Dislocations define a great many properties of crystalline materials. In addition to a crystal’s ability to yield and flow under stress, dislocations also control other mechanical behaviors such as creep and fatigue, ductility and brittleness, indentation hardness and friction. Furthermore, dislocations affect how a crystal grows from solution, how a nuclear reactor wall material is damaged by radiation, and whether or not a semiconductor chip in an electronic device will function properly. It can take an entire book just to describe the various roles dislocations play in materials behavior. However, the focus of this book is on the various computational models that have been developed to study dislocations. This chapter is an introduction to the basics of dislocations, setting the stage for subsequent discussions of computational models and associated numerical issues. Like any other crystal defect, dislocations are best defined with respect to the host crystal structure. We begin our discussion by presenting in Section 1.1 the basic elements and common terminology used to describe perfect crystal structures. Section 1.2 introduces the dislocation as a defect in the crystal lattice and discusses some of its essential properties. Section 1.3 discusses forces on dislocations and atomistic mechanisms for dislocation motion.

*Adrian P Sutton*

- Published in print:
- 2021
- Published Online:
- September 2021
- ISBN:
- 9780192846839
- eISBN:
- 9780191938764
- Item type:
- book

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780192846839.001.0001
- Subject:
- Physics, Condensed Matter Physics / Materials, Theoretical, Computational, and Statistical Physics

This short book describes ten fundamental concepts – big ideas – of materials science. Some of them come from mainstream physics and chemistry, including thermodynamic stability and phase diagrams, ...
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This short book describes ten fundamental concepts – big ideas – of materials science. Some of them come from mainstream physics and chemistry, including thermodynamic stability and phase diagrams, symmetry, and quantum behaviour. Others are about restless atomic motion and thermal fluctuations, defects in crystalline materials as the agents of change in materials, nanoscience and nanotechnology, materials design and materials discovery, metamaterials, and biological matter as a material. A cornerstone of materials science is the idea that materials are complex systems that interact with their environments and display the emergence of new science from the collective behaviour of atoms and defects. Great attention is paid to the clarity of explanations using only high school algebra and quoting the occasional useful formula. Exceptionally, elementary calculus is used in the chapter on metamaterials. It is not a text-book, but it offers undergraduates and their teachers a unique overview and insight into materials science. It may also help graduates of other subjects to decide whether to study materials science at postgraduate level.Less

This short book describes ten fundamental concepts – big ideas – of materials science. Some of them come from mainstream physics and chemistry, including thermodynamic stability and phase diagrams, symmetry, and quantum behaviour. Others are about restless atomic motion and thermal fluctuations, defects in crystalline materials as the agents of change in materials, nanoscience and nanotechnology, materials design and materials discovery, metamaterials, and biological matter as a material. A cornerstone of materials science is the idea that materials are complex systems that interact with their environments and display the emergence of new science from the collective behaviour of atoms and defects. Great attention is paid to the clarity of explanations using only high school algebra and quoting the occasional useful formula. Exceptionally, elementary calculus is used in the chapter on metamaterials. It is not a text-book, but it offers undergraduates and their teachers a unique overview and insight into materials science. It may also help graduates of other subjects to decide whether to study materials science at postgraduate level.