Breakdown phenomena in high-speed dislocations

Abstract

An analytical solution is presented for the atomic displacements in the steady motion of a dislocation in a modified Frenkel-Kontorova model of the form treated previously by Atkinson and Cabrera. It is found that at a critical dislocation velocity, here termed the breakdown velocity, ν B, the regular dislocation motion postulated a priori breaks down, so that the analytical solution is not valid for dislocation velocities ν ≥ ν B. Furthermore, ν B is less than the corresponding macroscopic sound velocity for this model. The results of computer-simulation studies of the behavior of the model at stress levels greater than those which cause dislocation breakdown are also presented.