Hydrogen absorption characteristics of Pd-Cr and Pd-Mo solid solution alloys

Thermodynamic parameters for absorption of hydrogen by Pd-Cr and Pd-Mo solid solution alloys containing up to 10.0 at.% Cr(Mo) have been determined from measurements of pressure-composition isotherms at temperatures between 273 K and 433 K and hydrogen pressures up to 1000 torr. The lower and/or higher pressure solubilities of hydrogen in both alloys decrease with increasing Cr and Mo contents; especially the solubilities in high Mo content Pd-Mo alloys are markedly small. The plateau pressure of (α+β) two-phase mixture in Pd-Cr and Pd-Mo alloys increases with the solute metal content. The relative partial molar enthalpy at infinite dilution, ΔHH0 in both alloys becomes less exothermic with the solute metal content and at the same alloy composition, the ΔHH0 values in Pd-Cr alloys are less exothermic than those in Pd-Mo alloys.