Self-diffusion mechanism in Ni-based L1₂ type intermetallic compounds

Abstract

We propose a model for the self-diffusion in L1₂ type A₃B ordered compounds. In this structure, the atoms of the major element A can diffuse on their own sublattice (α sublattice) via the ordinary vacancy mechanism without disturbing the ordered arrangement. For the atoms of the minor element B, the same mechanism is possible for those distributed over the α sublattice as antisite atoms. If the number of the antisite atoms is not negligibly small, the long-range diffusion of B can be due largely to their migration over the α sublattice as impurity diffusion. The self-diffusion data in Ni₃Al, Ni₃Ga and Ni₃Ge are discussed in the light of this model.