Atomic transport in ordered compounds mediated by local disorder: Diffusion in $B2{\text{-Ni}}_{x}{\text{Al}}_{1\ensuremath{-}x}$

Atomic transport in ordered compounds mediated by local disorder: Diffusion in $B 2 {-Ni}_{x} {Al}_{1 - x}$

Qingchuan Xu and Anton Van der Ven

Phys. Rev. B 81, 064303 – Published 26 February 2010

Abstract

Although $B 2 -NiAl$ has one of the simplest crystal structures of any intermetallic compound, its atomic transport mechanisms are complex and remain poorly understood. Here, we report on a first-principles study of diffusion in $B 2 -NiAl$ that simultaneously accounts for all relevant hop mechanisms in kinetic Monte Carlo simulations. Diffusion in $B 2 -NiAl$ occurs not only through first- and second-nearest-neighbor hops, but also through simultaneous pair-atom hops with the dominant transport mechanism being very sensitive to the bulk alloy concentration and degree of local disorder.