Atomic mobility was characterized by investigating the isothermal relaxation of short-range order in a Ni(Al,Ti) solid solution, and of long-range order in three intermetallic compounds Ni3Al, Ni3(Al,Ti) and Ni3(Al,Ta), by means of residual resistivity measurements. The relaxation in the intermetallics was much slower than in the solid solutions and in both cases the kinetics were strongly affected by a partial replacement of Al by Ti or Ta. The application of power-law kinetics led to the determination of relaxation time-constants and, in the solid solutions, to the corresponding activation enthalpies for self-diffusion.

Influence of Structure and Composition on Atomic Mobility in Ni(Al)-Based Solid Solutions and Ni3Al-Based Intermetallics. Tarfa, T., Dimitrov, C., Dimitrov, O.: Journal de Physique, 1993, 3[7], 453-6