It was noted that impurity diffusion in α-Ti was characterized by the fast interstitial diffusion of small atoms and the slow substitutional diffusion of large atoms. The mechanism of fast diffusion was considered on the basis of several features: the effect of α-β phase transformation, the diffusion anisotropy, the atomic size effect and the correlation between solubility and diffusivity. The temperature dependence of the diffusion coefficients of all the solutes, and of Ti, obeyed the Arrhenius law.

Diffusion in α-Ti and Zr. R.A.Perez, H.Nakajima, F.Dyment: Materials Transactions, 2003, 44[1], 2-13