Using a semi-empirical N-body potential and a conjugate gradient algorithm, diffusion activation energies in an L12-ordered Ni3Al-alloy were calculated. Stable and saddle-point configurations of vacancy jumps were evaluated, taking atomic and volume relaxations into account. The important influence of these relaxations in the search for saddle points, as compared to a rigid lattice, was demonstrated. Several mono-vacancy jump mechanisms including correlated jump sequences were investigated. In particular, attention was focussed on those diffusion mechanisms that were potential contributions to the experimentally observed but theoretically disputed fast self-diffusion of Al in Ni3Al.

The Influence of Lattice Relaxations on the Calculation of Diffusion Activation Barriers in an Ordered Ni3Al-Alloy. Schmidt, C., Bocquet, J.L.: Metal Physics and Advanced Technologies, 2001, 19[1], 45-53. See also: Metallofizika i Noveishie Tekhnologii, 1999, 21[1], 30-5