Influence of high stacking-fault energy on the dissociation mechanisms of misfit dislocations at semi-coherent interfaces

Abstract

By introducing constituent phases with high stacking fault energy (SFE), we have investigated the dissociation mechanisms of misfit dislocations existing in several semi-coherent interfaces using atomistic simulations and interface dislocation theory. Under large misfit dislocation spacing induced by huge lattice mismatch, misfit dislocation will dissociate independently with little influence of SFE. Meanwhile, the formation of a twin structure via dislocation climbing and the generation of Kink structure is found. When the dislocation spacing is sufficiently small, the supposed dissociated defect structure based on the geometric analysis becomes energetically unfavorable due to the high SFE, and distinct dissociation processes of the misfit dislocations occur: the dissociation of the dislocations at certain nucleate sites is hindered; the misfit dislocation decomposes towards bilateral phases rather than to only one of the constitute phase; the dissociation direction is reversed. Our work presents a novel understanding on the plastic-deformation mechanisms of semi-coherent interfaces and provides several feasible solutions to tune defect structures for material strengthening by introducing constitute phases with high SFE, controlling misfit parameters and applying different loading schemes.