A new model for dislocation kink-pair activation at low temperatures based on the Peierls-Nabarro concept

Abstract

The generation of double kinks in sessile screw dislocation cores is a highly nonlinear process but is the rate-controlling step for plasticity at low temperatures. In this work, double-kink generation in threefold screw dislocations in bcc crystals is studied within the framework of the Peierls-Nabarro (P-N) model in which the partial dislocations are described by non-singular displacement fields. The kink geometry is modelled by dividing the dislocation into elemental slabs, each of which is assumed to have its own displacement field calculated using the P-N model under the plane-strain condition. Explicit expressions for the apparent activation energy and volume have been obtained as a function of applied stress.