The interdiffusion coefficients in -phase material were determined by using Matano’s method, and couples of Ti-1.02Si with pure Ti, at temperatures ranging from 1173 to 1823K. By extrapolating the concentration dependence of the interdiffusion coefficient to infinite dilution, the impurity diffusion coefficients of Si (table 283) were determined. The Arrhenius plots for impurity diffusion exhibited an upward curvature which was similar to that observed for self-diffusion. The curvature was attributed to the effect of phonon-assisted diffusion jumps via monovacancies with a temperature-dependent migration energy. It was found that the activation energies for self-diffusion in the present host were proportional to the square of the radius of the diffusing atom. It was concluded that the size effect predominated during impurity diffusion.

Y.Iijima, S.Y.Lee, K.Hirano: Philosophical Magazine A, 1993, 68[5], 901-14

Table 282

Diffusion of Si in α-Ti