Bulk and grain-boundary self-diffusion and substitutional solute diffusion in group-IV hexagonal close-packed metals (α-Zr) were reviewed. Recent results obtained using high-purity materials were shown to approach closely the so-called intrinsic diffusion characteristics. The enhancement effect of fast-diffusing impurities (such as Fe, Ni, or Co) was considered, for both self- and substitutional bulk solute diffusion, in terms of the interstitial solubility of the impurity atoms. In grain-boundary self-diffusion, the impurity effect was found to be less marked. The results obtained for high-purity hexagonal close-packed materials could be interpreted in terms of intrinsically so-called normal vacancy-mediated grain-boundary diffusion, with a ratio of grain-boundary to volume diffusion activation enthalpy of about 0.6. The grain-boundary self-diffusion in group-IV hexagonal close-packed metals revealed distinct trends.

Bulk and Interface Boundary Diffusion in Group IV Hexagonal Close-Packed Metals and Alloys. C.Herzig, Y.Mishin, S.Divinski: Metallurgical and Materials Transactions A, 2002, 33[3A], 765-75