Niobium self-diffusion

The diffusion of ⁹⁵Nb in niobium has been measured between 1353 and 2693 K. The data showed nonlinear Arrhenius behavior and fit the expression D=[8×10^-3exp(-3.62 eV/kT)+3.7exp(-4.54 eV/kT)] cm²{sec}^{{-}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 O₂ and samples with less than 10-wt-ppm O₂.