The diffusion of Cr along the α/β interphase boundaries of Zr-2.5wt%Nb was studied by using conventional radiotracer and serial sectioning techniques. Arrhenius plots revealed a single straight line (with E = 133kJ/mol) at 615 to 953K, or 2 zones (with E = 230kJ/mol at 773 to 953K and E = 77kJ/mol at 615 to 773K). The analysis of these results was combined with previous data on short-circuit diffusion in α-Zr (grain boundaries) and Zr-2.5wt%Nb (interphase boundaries); with Zr and Nb as alloy components and Ni, Fe and Co as relevant impurities. Various mechanisms were proposed: a vacancy mechanism for Zr and Nb and an interstitial-like mechanism for impurities; for both kinds of boundary.

Diffusion along Grain and Interphase Boundaries in Alpha Zr and Zr-2.5wt%Nb Alloy. M.J.Iribarren, M.M.Iglesias, F.Dyment: Metallurgical and Materials Transactions A, 2002, 32[3A], 797-800