Partially pinned tilt boundaries

Abstract

This paper presents the results of a theoretical study of the conditions under which small angle tilt boundaries in a crystal can be moved when subjected to a stress which does not produce general slip. The dislocations in the boundary are assumed to be partially pinned by Cottrell atmospheres, intersecting substructure, or precipitates along the dislocation lines. The results show that partially pinned dislocation boundaries may move at lower stresses than similarly pinned isolated dislocations if the density of pinned segments is sufficiently low. Stress concentrations at pinned segments on a small angle boundary are discussed. A "yield condition" for motion of certain partially pinned boundaries is described in which pinned dislocations are left behind when the boundary is moved.

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