Interdiffusion coefficients in the β-phase of Ti-Al alloys were determined by using Matano's method at 1323 to 1823K using (pure Ti)/(Ti-8.5at%Al), (pure Ti)/(Ti-16.5at%Al) and (Ti-8.5at%Al)/(Ti-16.5at%Al) couples. Over the whole temperature range, the interdiffusion coefficient increased gradually with increasing aluminum content. The Arrhenius plot of the interdiffusion coefficient up to 6at%Al revealed an upward curvature similar to that seen for self-diffusion in β-Ti. The curvature became small with increasing aluminum content, and it was nearly linear at concentrations above 10at%Al. The activation energies for the impurity diffusion in β-Ti were proportional to the square of radius of the diffusing atom. This suggested that the size effect was dominant in the impurity diffusion in β-Ti.

Diffusion of Aluminum in β-Titanium. S.Y.Lee, O.Taguchi, Y.Iijima: Materials Transactions, 2010, 51[10], 1809-13