The absorption of hydrogen by binary vanadium-chromium alloys

The thermodynamic parameters of the solution of hydrogen in binary vanadium-chromium alloys (to 20 at. % Cr) have been determined. The partial molar enthalpy at infinite dilution increases with increasing Cr content (values range from ?7615 cal/H in pure vanadium to ?5891 cal/H in V/19.96 at. % Cr). The partial molar entropy of solution is unaffected by the presence of Cr. It is suggested that this behavior indicates that Cr atoms do not block potentially available interstitial sites for occupation by hydrogen. The apparent H-H interaction is diminished by the presence of Cr. The stability of the dihydride is decreased by Cr additions, to the point that V/19.96 at. % Cr does not form a dihydride (?78°C, 68 atm). X-ray data indicate that the structural characteristics of the alloy hydrides are similar to those observed in vanadium/hydrogen.