Dissolution of hydrogen and deuterium in titanium, Ti94Al6 and Ti3Al

Abstract

The solubility of hydrogen and deuterium in α-, α,β- and β-titanium, Ti₉₄Al₆ and in α₂-Ti₃Al has been volumetrically measured in the ranges of temperature 623–1323 K and hydrogen concentration (atomic ratio) 0.001–0.25. The equilibrium hydrogen pressure at a given temperature and hydrogen concentration has been found to increase greatly as the aluminium content increases. This is explicable on the assumption that aluminium atoms block some of the sites available to hydrogen atoms. In contrast, the heat of solution of hydrogen only slightly increases with the aluminium content and in α-titanium, α-Ti₉₄Al₆ and α₂-Ti₃Al, the ratio of the deuterium pressure to the hydrogen pressure at identical hydrogen and deuterium concentrations is almost independent of the aluminium content. A possible cause of the small dependence of the measured heat and ratio on the aluminium content is discussed and occupation of the tetrahedral site by hydrogen atoms is suggested for α-titanium, α-T₉₄Al₆ and α₂-Ti₃Al. The origin of the sloping plateaus observed in the pressure–composition isotherms for α, β-Ti₉₄Al₆ is also briefly discussed.