The Size Effect of Thin Films on the Peierls Stress of Edge Dislocations

Abstract

In this paper, we have developed a half-space Peierls—Nabarro (HSPN) model to evaluate dislocation mobility on material surface. The free-surface induced size effect on the mobility of an edge dislocation in thin films is investigated by using the model. The thickness of the thin layer between the dislocation and the free surface significantly influences the mobility of the dislocation. The Peierls stress of the edge dislocation in a thin film may be expressed as a function of the thickness of the thin film. A closed-form solution is obtained for the scaling factor, defined as the ratio of the modified Peierls stress to the conventional one in bulk materials, which allows for the characterization of the size (depth) effect on the Peierls stress of the edge dislocation in the half-space. Depending on the core size of the dislocation, the Peierls stress of a surface edge dislocation is about 5% to 25% less than that found in bulk materials.