Molecular dynamics simulations were made of the role played by vacancy diffusion in the surface ordering of (00l) faces. It was found that vacancy diffusion proceeded preferentially by hopping along the [110] direction. Each vacancy hop led to unstable atomic arrangements having a clear preference for recovering the initial surface order. These findings could be used to understand the order–order kinetics which characterized the Ni3Al(00l) face. It was found that the Al and Ni vacancies had constant hopping frequencies that exhibited an Arrhenius behavior, while surface disorder was also predicted at high temperatures.

Vacancy Diffusion Driven Surface Rearrangement in the Cu3Au(001) and Ni3Al(001) Surfaces. Lekka, C.E., Evangelakis, G.A.: Applied Surface Science, 2003, 205[1-4], 280-8