Compositional dependence of hydriding properties of vanadium alloys at low hydrogen pressures

The alloying effects have been investigated experimentally on the hydriding properties of vanadium at low hydrogen pressures. The PCT curves for the β phase (V2H or VH) are measured using an electrochemical method. It is found that the logarithm of the plateau pressure for the V2H and the VH phases change almost linearly with the amount of alloying element in vanadium metal. Also, when the Ti/Cr compositional ratio is fixed at 1, the equilibrium hydrogen pressure increases for the V2H phase but decreases for the VH phase with increasing total content of Ti and Cr. However, both the V2H and the VH phases become unstable with decreasing Ti/Cr compositional ratio, so that the PCT curve shifts towards the lower H/M side and the second plateau region for the VH2 phase existing at high hydrogen pressures spreads to some extent, which leads to the improvement in the effective hydrogen capacity of the alloy