THE DILUTE-SOLUTION OF HYDROGEN AND DEUTERIUM IN (C-15) TICR1.8

The dilute solution of hydrogen (and deuterium) in the intermetallic compound TiCr1.8 differs significantly from the behavior exhibited by hydrogen in pure metals and in random binary alloys. Specifically, i) the solution of hydrogen in TiCr1.8 exhibits pronounced positive deviation from Sieverts' Law; ii) the artial molar enthalpy at infinite dilution, ΔHH0=-35.0 kJ/H is significantly more exothermic than the enthalpy of β-hydride formation from homogeneous α-phase solution and hydrogen: [formula omitted] iii) the relative partial molar enthalpy of solution of hydrogen increases with increasing hydrogen content; iv) the excess free energy of hydrogen solution increases with hydrogen content. These results parallel the behavior of hydrogen in the intermetallic LaNi5 [1], and suggest the intriguing possibility that such behavior is common to the solution of hydrogen in all intermetallic compounds. A comparison of the solubility of hydrogen and deuterium in TiCr1.8 allows an estimation of the hydrogen vibrational frequency, vH ≃ 1530 cm-1. X-ray diffraction data reveal that the partial molar volume of hydrogen in TiCr1.8, VH = 1.51cm3, in close agreement with the value generally observed in pure metals or random binary alloys. © 1979, Akademische Verlagsgesellschaft.