The mechanisms of diffusion in the anomalous BCC metals

Abstract

A re-examination of tracer diffusion data for the anomalous BCC metals, beta -Ti and beta -Zr, at temperatures below 1250 degrees C, indicates the existence of two basic diffusion mechanisms. Recently extended tracer diffusion studies in Zr are consistent with a previous assumption that very fast solute diffusion in these anomalous metals is primarily due to an intrinsic interstitial mechanisms. Results for self, or substitutional, diffusion in these metals indicate an intrinsic defect mechanism, which is identified with the lattice vacancy. An assessment of tracer diffusion studies in the beta -Zr-Co system (<or=2 at% Co), in the light of these hypotheses, suggests extensive dissolution of Co in the interstitial sublattice.