Solubility of hydrogen and deuterium at low concentration in Fe0.5Ti0.5

Abstract

The concentrations of hydrogen and deuterium dissolved in Fe_0.5Ti_0.5 in equilibrium with the gas (pressure range, 0-120 bar; temperature range, 400-800K) were determined by electrical resistivity measurements. For both isotopes the electrical resistivity increases by 820 mu Omega cm per unit concentration of x in Fe_0.5Ti_0.5H_x/D_x. Hydrogen and deuterium dissolve endothermically, and Sieverts' law is satisfied up to the highest obtainable concentration (x approximately 0.03). For Fe_0.5Ti_0.5H_x the x-p-T relation (with p in bar, T in K) is log₁₀x=¹/₂log₁₀p-1.86-556/T. The partial molar enthalpies and excess entropies of solution at infinite dilution exhibit only a small isotope dependence. The solvus concentration of the solid solution Fe_0.5Ti_0.5H_x is log₁₀x=1.1-1340/T.