On the properties of 〈111〉 {110} dissociated superdislocation in B2 structure YAg and YCu: Core structure and Peierls stress

Abstract

The simplified one-dimensional dislocation equation for mixed dislocations is derived briefly from the two-dimensional modified Peierls-Nabarro equation taking into account the discreteness effect of crystals. The collinear dissociated core structure of 〈111〉 {110} superdislocations in the novel B2 structure YAg and YCu are investigated with the simplified equation. Both the core width and the dissociated width are increasing with the increases in the dislocation angle of superdislocations. The dissociated width determined by continuum elastic theory is inaccurate for the high antiphase boundary energy but is recovered for the low antiphase boundary energy. The Peierls stress of the dissociated dislocation is replaced by that of superpartials. The results show that both the unstable stacking fault energy and the core width are crucial for the Peierls stress in the case of a narrow core structure. However, the core width becomes the main factor in controlling the Peierls stress in the case of a wide core.