High‐temperature strength of dispersion-hardened single crystals II. Theory

Abstract

A theory of the yield stress of dispersion-hardened single crystals as a function of temperature and strain rate is described. This theory assumes that the dislocations remain on their slip planes, except at some particles which the dislocations by-pass by climbing locally over these particles. The number of particles by-passed by local climb depends on the strain rate and temperature. A computer programme which simulates a dislocation going through a random array of point obstacles some of which are by-passed by climb is described. The relation between yield stress, temperature and strain rate obtained using this programme agrees reasonably well with experiment. The most important result of the calculations is that the dislocation velocity can depend exponentially on the applied stress even though the time required for the dislocation to overcome an individual obstacle depends only weakly on the stress.