Solubility and diffusivity of hydrogen and deuterium in TZM

Abstract

A gas evolution method has been used to study the interaction of hydrogen and deuterium with TZM, a potential NET divertor material. Temperatures in the range 673–873 K and loading pressures between 10 3 and 10 5 Pa have been used. Hydrogen and deuterium dissolve exothermally in TZM, despite the dominant presence of Mo, which is an endothermal occluder of hydrogen. Their solubility is quite low, i.e. in the range 0.1–1 mol m −3, but higher than in Mo, 10 times at 873 K. The diffusivity obtained after data fitting with a simple diffusion-limited model is 10 times lower than in Mo, in the range 1 × 10 −11-5 × 10 −10m 2s −1. Surface effects are present and are analyzed on the basis of a simple surface-li mited kinetic model. The hydrogen and deuterium data obtained have been used for tritium extrapolation of solubility and diffusivity.