Radio-tracer diffusion measurements of 63Ni were performed in Ni75AlxGe25-x ternary intermetallic compounds at various temperatures (table 31). The tracer diffusivity was found to depend exponentially on the Ge content of the alloy. These compounds were ordered with the L12 structure, where the Ni atom diffusion proceeds mainly via Ni sublattice site jumps. The change of the diffusivity could be attributed to the change in vacancy concentration on the Ni sub-lattice as well as to the composition dependence of the saddle-point energy of the diffusion jumps.

Tracer Diffusion of 63Ni in Ni3(Al,Ge) Ternary Intermetallic Compound. Cserháti, C., Szabó, I.A., Márton, Z., Erdélyi, G.: Intermetallics, 2002, 10[9], 887-92

Table 28

Arrhenius parameters for grain-boundary 63Ni diffusion in Ni3Al