Atomic structure variations of mechanically stable fcc-bcc interfaces

Abstract

It has recently been shown that under severe plastic deformation processing bi-metal fcc/bcc composites develop a mechanically stable heterophase interface that joins the {112}fcc//{112}bcc planes in the Kurdjumov-Sachs orientation relationship. In this article, we study variations in the relaxed equilibrium atomic structure of this interface with changes in fcc stacking fault energy (SFE) and lattice mismatch between the two crystals. Using molecular statics/dynamics simulations for three fcc/bcc systems, Cu-Nb, Al-Fe, and Al-Nb, we find that the number of distinct sets of intrinsic interfacial dislocations and their core structures vary significantly among these three systems. The impact of these atomic-scale structural differences on interfacial properties is demonstrated through their interactions with point defects. The interfaces studied here are shown to exhibit a wide variation in ability, ranging from being a poor to an excellent sink for vacancies.