Niobium self-diffusion

Abstract

The diffusion of $^{95}\mathrm{Nb}$ in niobium has been measured between 1353 and 2693 K. The data showed nonlinear Arrhenius behavior and fit the expression $D=[8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\mathrm{exp}(\ensuremath{-}3.62 \mathrm{eV}/\mathrm{kT})+3.7\mathrm{exp}(\ensuremath{-}4.54 \mathrm{eV}/\mathrm{kT})]$ ${\mathrm{cm}}^{2}$${\mathrm{sec}}^{\ensuremath{-}1}$. The data are interpreted in terms of a single-vacancy-divacancy mechanism. The effect of oxygen on niobium self-diffusion was measured over the temperature range 1750-2690 K. There was no measurable difference in the diffusion coefficient obtained from samples with 500-wt-ppm ${\mathrm{O}}_{2}$ and samples with less than 10-wt-ppm ${\mathrm{O}}_{2}$.