SOLUBILITY OF HYDROGEN AND DEUTERIUM IN ZRCO

This paper gives first results on the solubility of hydrogen and deuterium in ZrCo in the composition range 2X10(-3) <(n(H) or n(D))/n(ZrCo)<10(-1) as a function of temperature. Sieverts' constants (K-S)(D or H) were obtained in the temperature range 473-773 K. The ratio (K-s)(H)/(K-S)(D) was found to be 1.182+/-0.035. The relative partial molar enthalpies Delta (H) over bar(Q)(infinity) (Q = H, D) and the nonconfigurational or excess entropies Delta S-Q(nc) at infinite dilution were calculated to be Delta (H) over bar(H)(infinity)=-28.2 kJ/mol(H), Delta (H) over bar(D)(infinity) = - 27.7 kJ/mol(D), Delta (S) over bar(H)(nc infinity)=-73.5 J/K mol(H), and Delta (S) over bar(D)(nc infinity)=-74.2 J/K mol(D), respectively. Whereas the partial molar enthalpies Delta (H) over bar(Q) were found to be largely independent of the x(Q) n(Q)/n(ZrCo) ratio in the intermetallic compound, the negative partial molar entropies Delta (S) over bar(Q) were observed to increase with x(Q).