Tracer diffusion of 63Ni in Ni3(Al,Ge) ternary intermetallic compound

Radio-tracer diffusion measurements of 63Ni have been performed in Ni75AlxGe25−x ternary intermetallic compounds at various temperatures. The tracer diffusivity was found to depend exponentially on the Ge content of the alloy. These compounds are ordered with the L12 structure, where the Ni atom diffusion proceeds mainly via Ni sublattice site jumps. The change of the diffusivity can be attributed to the change in vacancy concentration on the Ni sublattice as well as to the composition dependence of the saddle-point energy of the diffusion jumps.