Thermal and mechanical properties of Hf hydrides with various hydrogen content

Fine bulk samples of delta-phase Hf hydride with various hydrogen contents (C_H) ranging from 1.62 to 1.72 in the atomic ratio (H/Hf) were prepared, and their thermal and mechanical properties were characterized. In the temperature range from room temperature to around 650 K, the heat capacity and thermal diffusivity of the samples were measured and the thermal conductivity was evacuated. The elastic modulus was calculated from the measured sound velocity. The Vickers hardness was measured at room temperature. Effects of C_H and/or temperature on the properties of Hf hydrides were discussed. At room temperature, the thermal conductivity values of the Hf hydrides were 23 Wm^-1K^-1. The Young's and shear moduli and the Vickers hardness of Hf hydride decreased with increasing C_H.