Supersonic Dislocation Kinetics from an Augmented Peierls Model.

The controversial issue of whether dislocations can travel faster than shear or longitudinal waves is investigated. The Peierls model, modified to account for drag and gradient effects, furnishes a kinetic relation between the applied shear stress and speed of uniformly moving dislocations. This relation predicts intersonic and supersonic speeds at high enough stress, but also regimes of unstable motion, in agreement with recent atomistic simulations.