Impurity diffusion in α-Zr 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 of the elements studied (with the exception of Ti) exhibited downward curvatures that followed the self-diffusion behaviour in α-Zr.

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