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

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