On the mechanism of cross slip in Ni \u3c inf\u3e 3 AI

The mechanical properties of Ll2 intermetallic alloys have been previously described by models based on the assumption that cube cross slip is the rate-limiting step. In this study, it was demonstrated that the cube cross-slip event must be reversible under a change in loading direction. This observation allows the cross-slip models to remain consistent with cyclic deformation data. Additionally, this observation was used as a critical test of the available cross-slip models. It was demonstrated that the rate-limiting step cannot be a total cross-slip event, in which both α/2(110) superpartial dislocations cross slip to the cube plane. Conversely, the limited cross-slip event proposed by Paidar, Pope, and Vitek (PPV) was demonstrated to be consistent with the reversibility constraint. This lends additional experimental support to the PPV model. © 1989 The Metallurgical Society of AIME