Diffusion parameters of Cr diffusion along the α/β interphase boundaries of a Zr-2.5wt%Nb alloy were presented. The conventional radiotracer technique, combined with serial sectioning, was used. In the Arrhenius plot, it was possible to identify just one straight line (with Q = 133kJ/mol at 615 to 953K) or 2 zones (with Q = 230kJ/mol at 773 to 953K and Q = 77kJ/mol at 615 to 773K). An analysis was made of these results together with previous data concerning diffusion along short-circuit paths in α-Zr (grain boundaries) and Zr-2.5wt%Nb (interphase boundaries); Zr and Nb as the alloy component elements and Ni, Fe, and Co as other relevant impurities. Different mechanisms were proposed; a vacancy mechanism for Zr and Nb and an interstitial-like mechanism for the impurities, for both types of boundary.

M.J.Iribarren, M.M.Iglesias, F.Dyment: Metallurgical and Materials Transactions A, 2002, 33[3A], 797-800

Table 335

Diffusivity of Cr in Zr