Abstract
Interdiffusion coefficients in the β-phase of Ti-Si, Ti-Ge and Ti-Sn alloys have been determined by Matano's method in the temperature range between 1173 and 1823 K with (pure Ti)-(Ti-102 at.%Si alloy), (pure Ti)-(Ti-2.00at.% Ge alloy) and (pure Ti)-(Ti-1-65at.%Sn alloy) couples. By extrapolating the concentration dependence of the interdiffusion coefficient to the infinite dilution of solute, the impurity diffusion coefficients of Si, Ge and Sn in β-Ti have been determined. In the whole temperature range of the present experiments, the relation DSi>DGe>D*Ti>DSn has been recognized. The Arrhenius plot of the impurity diffusion coefficients shows an upward curvature similar to that recognized in the self-diffusion in β-Ti. The curvature in the Arrhenius plots has been explained by the mechanism of phonon-assisted diffusion jumps via monovacancies with a temperature-dependent migration energy in β-Ti. The activation energies for the impurity diffusion and self-diffusion in β-Ti are proportional to the square of radius of the diffusing atom. This suggests that the size effect is dominant in the impurity diffusion in β-Ti.