Diffusion and electrotransport of hydrogen and deuterium in vanadium-titanium and vanadium-chromium alloys

The diffusion coefficient D and electrotransport effective charge number Z* of hydrogen and deuterium in V, V1-xTix, and V1-yCry were measured as a function of temperature using resistance techniques. Measurements were performed for hydrogen (deuterium) concentrations of approximately 1 at.% and alloys with x=0.03 and 0.08 and y=0.04 and 0.10. Alloying vanadium with either titanium or chromium was found to lower both D and Z* over the entire temperature range studied (310-480 K). The diffusion data obey an Arrhenius relation, the alloys having larger activation energies for diffusion than pure vanadium. No currently existing microscopic theory seems capable of explaining the dependence of D on alloy composition, nor can the data be consistently explained by a simple two-state trapping model. In every sample, Z* was observed to decrease with increasing temperature and host-metal resistivity for both hydrogen and deuterium. In addition, Z* was found to be larger for deuterium than hydrogen.