Self-diffusion and interdiffusion in intermetallic compounds

Abstract

Abstract Recent studies on self-diffusion in L1 2 -type intermetallic compounds and interdiffusion in intermetallic compounds of a Ti–Al system are reviewed. In Ni 3 Ge compounds, the Ni diffusivity is two orders of magnitude higher than the Ge diffusivity; the major element diffuses faster than the minor element in L1 2 -type compounds. This trend is consistent with the expectation based on the geometrical arrangement of Ni and Ge in Ni 3 Ge. However, in Ni 3 Ga compounds, the Ni diffusivity is only 1.1–2.1 times larger than the Ga diffusivity in the temperature range 943–1112 K. This is explained by a mechanism of anti-site Ga diffusion in the Ni-sublattice in Ni 3 Ga compounds. Single-phase interdiffusion experiments are the most suitable to determine the interdiffusivity, which is much different from the data from multi-phase reaction diffusion experiments; the latter involves extrinsic effects such as grain boundary diffusion. The interdiffusion in TiAl and Ti 3 Al compounds is discussed with the self-diffusivities in terms of the Darken relation.