Diffusion in Ni3Al, Ni3Ga and Ni3Ge

An overview is given on recent progress in the study of atomic diffusion in three nickel-based L12-ordered intermetallic compounds, Ni3Al, Ni3Ga and Ni3Ge. Data of the diffusion of constituent species and those of chemical diffusion have been accumulated by radioactive tracer experiments and single-phase interdiffusion experiments. The tracer diffusion coefficients of the majority component, Ni, in the three compounds are of the same order of magnitude when normalized to the melting temperature, while in contrast, those of the minority component are widely different. Nevertheless, it appears possible to understand these common and distinctive features in terms of a simple model of diffusion, where both of the two species of atoms diffuse primarily over the sublattice of the majority component via the ordinary vacancy mechanism.