Shearing dominated by the coupling of the interfacial misfit and atomic bonding at the FCC (111) semi-coherent interfaces

Using atomistic simulations, we present a systematic investigation of the shear mechanisms of three {111} bimetal interfaces, focusing on the influence of the dislocation spacing and bonding scheme across the interface. The evolution of interface sliding process reveals that all the initial shearings are nucleated at the regions of dislocations and their nodes. The interface with small lattice misfit could accommodate the shear strain via the dislocation loops gliding into neighboring massive coherent regions, exhibiting a comparatively low shear strength. However, at the interface with dense dislocation network, the adjacent gliding dislocation loops interact with each other and prohibit further interface sliding. Considering the γ surfaces of three {111} interfaces, it is found that the miscellaneous bonding scheme across the interface can vary the preferred sliding directions and prevent the necessary transformation of the incipient sliding directions, which eventually increase the shear resistance. The shear strength of the Ni/Al {111} interface is increased by six times after alloying, verifying the cooperative strengthening effect contributed by the dense interfacial dislocations and miscellaneous bonding scheme.