On the diffusion in the Mo–Ta refractory system

Abstract Diffusion in the Mo–Ta system is studied as regards interdiffusion and impurity diffusion over the temperature range from 1500 to 1900 ° C . Interdiffusion coefficients, calculated with the den Broeder or Hall methods, are found to be weakly composition-dependent. Their temperature-dependence leads to Arrhenius parameters consistent with (i) literature data obtained at higher temperatures and (ii) a monovacancy mechanism. The composition-dependence of the Arrhenius parameters implies repulsive interactions between unlike atoms. Linear relationships between those parameters are found to exist among composition. Impurity diffusion coefficients DMo(Ta)0 and DTa(Mo)0 are determined by the Vignes and Birchenall method and are consistent with the interdiffusion coefficient limits. By comparison with literature data, anomalous behavior is obvious over the range 1500– 2220 ° C for both coefficients.