Interdiffusion in the Cu-(Ni-43at%Al) system was studied. It was shown that, in the diffusion zone, Cu atoms substituted mainly for Al atoms and that the diffusion process could be treated as being quasi-binary. The concentration dependences of the interdiffusion coefficients were determined at 923 to 1273K. A rapid increase in the interdiffusion coefficient in a narrow range of Cu concentrations was explained in terms of a percolation model. The calculated percolation threshold (6.06at%) for Cu atoms agreed well with experimental data.

Percolation Effects during Interdiffusion in the Cu-NiAl System. E.Rabkin, V.N.Semenov, A.Winkler: Acta Materialia, 2002, 50[12], 3229-39