Calculation of critical shapes and stresses of surface sources of dislocations

Abstract

An iterative method of computation has been applied to determine the activation stress of emerging segments of dislocations, anchored beneath the free surface, in the case of a homogeneous applied stress field. The calculation has been performed for a series of orientations of the Burgers vector and of source lengths. The results give exact information about the behaviour of surface sources as compared to that of internal ones. In particular, in contrast to internal Frank-Read sources, surface segments with Burgers vectors symmetrical with respect to the edge orientation exhibit different activation stresses.