Influence of interstitial elements on hydrogen solubility in the Group IV metals

Abstract

A comparison of hydrogen solubility and enthalpy of solution of hydrogen was performed for (Ti, Zr, Hf)-(O, N, C) binary solid solutions. Oxygen addition into titanium and hafnium decreased the hydrogen solubility at a fixed pressure. The hydrogen solubility in zirconium first increased with oxygen content, and then decreased at a higher oxygen content. The enthalpy of solution of hydrogen was lower for oxygen solid solutions than for pure metals. For all the metals, the presence of nitrogen and carbon increased the hydrogen solubility and provided a negative effect on the enthalpy of solution of hydrogen. Partial thermodynamic functions of hydrogen in (Ti, Zr, Hf)-(O, N, C)-H ternary solid solutions were estimated using a dilute solution model. The partial molar enthalpy and the partial molar excess entropy decreased with nitrogen and carbon contents in the solid solutions. The oxygen effect on partial molar quantities was more complex. The changes in the partial molar quantities with the composition of the solution were discussed in terms of vibrational. dilatometric, and configurational contributions.