Diffusion in complex ordered alloys: Atomic-scale investigation of NiAl3

Although involved in most solid-state processes, ordered compounds are often characterized by complex crystallographies and chemical properties, which drastically restricts the range of experimental investigations, and urges more realistic simulation frameworks. Considering the case of NiAl3 and the unknown diffusion properties of its practically important cementite-type structure, we use embedded-atom-method-based atomic-scale simulations to perform a detailed analysis of its kinetic parameters controlling jump rates, including migration profiles, saddle points and attempt frequencies. The global approach proposed here is made necessary by the intricate coupling between these quantities, which rules out more usual schemes relying on selected transitions. It provides the required material for atomistic simulations of diffusion in low-symmetry ordered phases.