The thermodynamic functions of hydrogen in solid solutions of the Group V metals Nb, Ta and V

The large volume of available data for the isotherms characterizing the disolution of H from H2-gas into the Group V metals Nb, Ta and V has been reviewed. Both the temperature and composition variation of the partial molar and relative partial molar enthalpies and entropies have been discussed in terms of theoretical models in which the H-atoms in solutions can possess degrees of translational freedom. The relative invariance of the relative partial enthalpy ΔHsub(u) to temperature and the change in Hsub(u) with temperature are in accord with this concept. The variation of Hsub(u) with solute composition has been used in conjunction with recent elastic data for H-Nb, H-Ta and H-V solid solutions to discuss the form of the H-H interaction in these systems. (Auth.)