Thermal and mechanical properties of zirconium hydride

Abstract

The physico–chemical properties of zirconium hydride such as mechanical and thermal properties have been studied in the present study. The zirconium hydride specimens in the form of pellets (6 mm φ×10 mm l) had the hydrogen contents with 1.5–1.7 H/Zr, which were fabricated directly from zirconium metal in a modified UHV Sieverts apparatus. All the zirconium hydrides prepared in the present study showed CaF2 type δ ZrH2−x. The lattice parameter slightly increased with the hydrogen content. The thermal expansion coefficients of the zirconium hydrides evaluated from high-temperature X-ray diffraction data were larger than that of zirconium metal and increased with the hydrogen content. The longitudinal and shear sound velocities of the zirconium hydride were slightly different from those of zirconium metal, which enabled us to estimate the elastic properties. The zirconium hydride had higher elastic moduli than zirconium metal and the elastic moduli slightly depended on the hydrogen content. The microhardness of the zirconium hydride was much higher than that of zirconium metal and decreased with increasing hydrogen content. The Debye temperature of the zirconium hydride estimated from the sound velocities was larger than that of pure zirconium metal. The heat capacity was also estimated from the sound velocities and the thermal expansion data.