Isotope Effect in Self-Diffusion in Iron

Abstract

The isotope effect in self-diffusion was measured in the $\ensuremath{\delta}$, $\ensuremath{\gamma}$, and $\ensuremath{\alpha}$ phases of Fe using a new isotope pair, ${\mathrm{Fe}}^{52}$-${\mathrm{Fe}}^{59}$. The isotope-effect data, together with measurements taken on the effect of Co solute additions on Fe self-diffusion, were used to deduce the most likely mechanisms for self-diffusion in all three phases. The data are consistent with a vacancy mechanism in fcc $\ensuremath{\gamma}\ensuremath{-}\mathrm{Fe}$. In bcc $\ensuremath{\alpha}$- and $\ensuremath{\delta}\ensuremath{-}\mathrm{Fe}$, the data are consistent with a vacancy or interstitialcy mechanism. The mechanism seems to be the same in $\ensuremath{\delta}$- and in $\ensuremath{\alpha}\ensuremath{-}\mathrm{Fe}$.