Mapping dislocation nucleation behavior from bimetal interfaces

Interfaces between two dissimilar metals have been observed to exhibit a range of atomic structures, from atomically flat to atomically stepped. Using atomic-scale simulation and theory, we study the influence of the intrinsic bimetal interface structure on the nucleation of lattice dislocations. Interface structure is found to have a strong effect on which dislocations are nucleated and the type of nucleation site. We develop a theoretical model that provides criteria for predicting these effects based on key structural relationships between the interface and adjoining crystals. In recognition of these critical conditions, we construct a map that identifies the most likely nucleation site from a given interface. The theory and map developed here can guide efforts to tune interface structures for controlling the strength and deformation of heterogeneous materials.