Atomistic Studies Of The Structure Of Grain Boundaries and Dislocations

Abstract

Grain boundaries and dislocations are the most common extended defects in crystalline materials. The principal difference between them is that grain boundaries are planar imperfections which are not accompanied by long-range strain and stress fields, while dislocations are line defects that produce long-range elastic strains and stresses in the material. They both strongly affect, and to a great extent control, the physical and mechanical properties of materials. This is the reason why both dislocations and grain boundaries, and also more general types of interfaces, have been studied very extensively throughout the development of materials science. A common feature of both grain boundaries and dislocations is that their basic characteristics are of crystallographic, geometrical nature. Indeed, in earlier structural studies these characteristics were the main topic of experimental and theoretical investigations (Bollman, 1970; Hirth and Lothe, 1982; Sutton, 1984; Sutton and Balluffi, 1995). In the case of dislocations they were closely linked with studies of their elastic fields and associated long-range interactions (Nabarro, 1967; Hirth and Lothe, 1982). Since crystallographic attributes of dislocations and grain boundaries have to be defined prior to any study of their structures and properties we summarize these characteristics briefly in the following section.