THE PEIERLS DISLOCATION - LINE ENERGY, LINE TENSION, DISSOCIATION ANDDEVIATION

Atomic simulations of the dislocation core show that the atomic misfit is often concentrated in the glide plane. Instead of using a step fun ction to describe the displacement as in a classical Volterra dislocat ion, a better description is obtained by a Peierls dislocation for whi ch the displacement is assumed to have an arctg like shape. The slope in the center is determined by requiring that the total energy must be a minimum. The elastic energy can be expressed in closed form, and wi th the availability of high speed computing the atomic misfit energy i n the glide plane can be calculated by standard numerical integration without any difficulties. When the Peierls model is extended to two di mensions the resulting line energy, line tension and resistance agains t bow-outs of straight dislocations can be obtained realistically with out any adjustable parameters and the way that these quantities are in fluenced by the interplanar atomic potential can be studied. In additi on to undergoing the well-known ''dissociation'', a mixed dislocation may lower its energy by a ''deviation'' in which the displacement vect or deviates from the direction of the crystallographic Burgers vector even when this runs along a path of lowest misfit energy. (C) 1997 Act a Metallurgica Inc.