Hydrogen embrittlement of bulk W-0.5 wt% ZrC alloy induced by annealing in hydrogen atmosphere

Annealing of a tungsten alloy containing 0.5 wt% zirconium carbide (WZC) in hydrogen atmosphere induced hydrogen embrittlement, which was investigated by exploring the evolution of the tungsten grain size and orientation, the second phase particles distribution, and the tensile properties of the hydrogen-containing and hydrogen-free WZC samples. Thermal desorption spectroscopy used to determine the hydrogen retention revealed a broad hydrogen desorption peak at 1000 – 1300 K, whose hydrogen origin was attributed to the trapping sites in the non-stoichiometric ZrCx of the WZC samples after annealing in hydrogen atmosphere at 1300 °C. Hydrogen retention resulted in the degradation of mechanical properties including strength and ductility and in the deterioration of the ductile-to-brittle-transition behavior. The results emphasize the importance of the atmosphere choice for annealing tungsten materials to avoid hydrogen embrittlement and to ensure good mechanical properties.