STATISTICAL TREATMENT OF PENETRABLE OBSTACLES

Abstract

Obstacles to dislocation motion which are pointlike in character, finite in strength, and random in spatial distribution in the slip plane, are treated by statistical methods developed previously for infinitely strong obstacles. Various important length parameters are distinguished and derived as functions of stress: the link length between obstacles relevant in internal friction problems, the passing distance defined by the flow stress, the differential activation length determining the rate dependence of the flow stress, and the free slip distance important in the elastoplastic transition region and in the preexponential factor for thermal activation. The flow stress results agree with those of Foreman and Makin, but the differential activation length and the free slip distance predicted show important effects not previously expected.