Bulk modulus of the solid solution of hydrogen in titanium at 673 K

Abstract

The bulk modulus of the solid solution of hydrogen in titanium is determined from the measurements of the modulus of rigidity and the Young’s modulus as a function of the hydrogen concentration at 673 K. These moduli give identical trends in their concentration dependence. As the hydrogen concentration increases, the moduli decrease steeply in the α-phase region, are almost constant in the (α+β)-coexisting-phase region, and increase less steeply in the β-phase region. On the other hand, the bulk modulus for the solid solution is evaluated in the electronic-band theory, in which the contribution of s-shell and d-shell electrons is considered. The spherical cellular model is applied to the calculation, in which the Wigner–Seitz radius is given as a function of the hydrogen concentration. The electronic contribution to the bulk modulus is represented by the effective mass parameter, which is determined by comparing the theoretical expression of the bulk modulus with the experimental data. The fact that there is a great dependence of the effective mass parameter on the hydrogen concentration suggests that the solid solution of hydrogen in titanium must be characterized in terms of its electronic structure.