Hydrogen desorption behavior of the hydrides of ZrY alloys under Ar and CO2 atmosphere

The crack-free bulk hydrides of ZrY alloys have been prepared and characterized by X-ray diffraction, optical microscopy and electron probe microanalysis to study the phase structure, microstructure and composition distribution, respectively. It was found that the as-received hydrides were composed of zirconium hydrides and yttrium hydrides mixtures. We performed thermogravimetry and simultaneous thermal desorption spectroscopy (TG/TDS) under Ar and CO2 atmosphere to study the effect of yttrium and surface oxide layer on hydrogen desorption from zirconium hydride. The results showed that zirconium hydrides containing higher Y content tend to have higher hydrogen desorption temperatures and higher hydrogen content, suggesting that hydrogen could be retained in the hydride matrix by alloying with yttrium. X-ray diffraction indicated that an oxide layer was formed on the surface of the metal hydrides under CO2 atmosphere, and yttrium could stabilize t-ZrO2 phase in the oxide layer, thus inhibiting hydrogen desorption from the metal hydrides at the reactor working temperature.