A first-principles study on interfacial properties of Ni(001)/Ni3Nb(001)

The Ni (001) surface, Ni3Nb (001) surface and Ni (001)/Ni3Nb (001) interfaces were studied using the first-principles pseudopotential plane-wave method. The adhesion work, thermal stability and electronic structure of Ni/Ni3Nb (001) interfaces were calculated to expound the influence of atom termination and stacking sequence on the interface strength and stability. Simulated results indicate that Ni and Ni3Nb (001) surface models with more than eight atomic layers exhibit bulk-like interior. The (Ni+Nb)-terminated interface with hollow site stacking has the largest cohesive strength and critical stress for crack propagation and the best thermal stability among the four models. This interfacial Ni and the first nearest neighbor Nb atoms form covalent bonds across the interface region, which are mainly contributed by Nb 4d and Ni 3d valence electrons. By comparison, the thermal stability of Ni/Ni3Nb (001) interfaces is worse than Ni/Ni3Al (001) interface, implying that the former is harder to form. But the Ni/Ni3Nb interface can improve the mechanical properties of Ni-based superalloys.