The concentration dependences of the diffusion coefficients of H and D in Nb and Ta, in the α and α′ phases, were measured between 0 and 40%H or D/Nb or Ta by using the Gorsky effect. Since this method permitted the simultaneous determination of the thermodynamic factor, the tracer-diffusion coefficient could be extracted from the data. An increase in the activation energy as a function of concentration was found for all of the systems. For Ta, an isotope-dependence of the diffusion coefficients continued to exist at high concentrations, while it disappeared for Nb.

Diffusion of Hydrogen and Deuterium in Nb and Ta at High Concentrations. H.C.Bauer, J.Völkl, J.Tretkowski, G.Alefeld: Zeitschrift für Physik B, 1978, 29[1], 17-26

Table 88

Parameters for H and D Diffusion in Nb at 0 to 100C