An analysis for interdiffusion coefficients and thermotransport coefficients in isothermal and nonisothermal ternary diffusion

A new analysis is presented for the determination of average values of the main and cross interdiffusion coefficients over selected composition ranges from the concentration profiles of an isothermal ternary diffusion couple. The analysis utilizes an integration of interdiffusion fluxes over selected regions in the diffusion zone. The analysis is applied to selected isothermal diffusion couples in the Cu-Ni-Zn and Fe-Ni-Al systems. The analysis is also extended to examine interdiffusion in a ternary alloy under a temperature gradient. The extended analysis is employed for the determination of interdiffusion coefficients and thermotransport coefficients as well as the diffusion flux contributions arising from the gradients of temperature and concentrations in a U-Pu-Zr alloy subjected to a temperature gradient.