Atomistic simulations of the shear strength and sliding mechanisms of copper–niobium interfaces

Interfaces play a prominent role in the deformation behavior of high-strength Cu–Nb layered composites by acting as barriers to slip transmission due to core spreading of glide dislocations within interfaces. The dislocation core spreading along the interfaces implies these interfaces are weak in shear. In this investigation, we have used atomistic simulations to explore the shear resistance and sliding mechanism of interfaces of Cu–Nb layered composites, as a function of applied in-plane shear direction and different interface atomic structures. The simulation results indicate that the shear strengths of Cu–Nb interfaces are: (i) lower than the theoretical estimates of shear strengths for perfect crystals, (ii) strongly anisotropic, (iii) spatially non-uniform and (iv) strongly dependent on the atomic structures of interfaces. The mechanism of interface sliding involves glide of interfacial dislocation loops that nucleate in the weakest regions of interfaces.