Intrinsic Diffusion, Mobility and Correlation Effect in Cu(Al) Solid Solution

Abstract

The diffusion behaviour of Al and Cu in Cu(Al) solid solution phase was investigated in the temperature range 1023–1223 K, by employing single-phase diffusion couples of Cu/Cu–10 at% Al. The intrinsic diffusion coefficient of Al was found to be higher than that of Cu in the solid solution phase. The thermodynamic factor for the Cu(Al) phase was calculated as a function of composition and temperature, assuming a regular solution behaviour. The tracer diffusion coefficients and mobilities of Al and Cu were also evaluated. The activation energies for intrinsic diffusion were 127.2 kJ mol⁻¹ and 146.7 kJ mol⁻¹, and those for tracer diffusion were 133.2 kJ mol⁻¹ and 152.6 kJ mol⁻¹ for Al and Cu, respectively. The correlation factor for Cu remained almost constant, while that of Al was found to have strong temperature dependence. The values of the correlation factors indicated a comparatively low concentration of vacancies involved in the diffusion process and the jump ratio of Al was an order of magnitude higher than that of the Cu.