Comments on α-β phase boundary self-diffusion in Zr-2.5% Nb alloys

Previously obtained 95Nb interphase diffusion coefficients were re-evaluated taking into account more recent β-phase lattice diffusivity values obtained by other authors. The new Arrhenius plot is a straight line if the lowest temperature point is neglected and the diffusion parameters, according to the Fisher-Bondy model, are Qi = (288±30) kJ/mol and D0i = (0.89±0.4)x104 m2/s, with δ = 5x10-10 m. The enhanced interphase diffusivity value for low temperatures with respect to the straight line is ascribed to the lack of structural stability of the samples during the diffusion anneal. This would affect more the Nb diffusion, because Nb is the minor component of the alloy, than the Zr diffusion. (orig.)