2016 年 15 巻 4 号 p. 223-228
Fe2B appears to have formed in the fuel debris at the Fukushima Daiichi nuclear disaster site through the reaction between stainless steel and the control material B4C. In order to conduct defueling operations, understanding the physical properties of Fe2B is of extreme importance. In the present study, we have prepared an Fe2B bulk sample with 92.5% theoretical density by spark plasma sintering of Fe2B powder, and we have evaluated the mechanical and thermal properties of the sample. The thermal diffusivity was measured by a laser flash method in an argon flow. The thermal conductivity was evaluated from the heat capacity, thermal diffusivity, and density. The electron thermal conductivity was calculated from measurement values of electric conductivity. The longitudinal and shear sound velocities were measured by a sing-around method at room temperature in air, which enables the elastic modulus and Debye temperature to be evaluated. The hardness measurements were performed at room temperature in air using a Vickers hardness tester. The fracture toughness was estimated from a crack produced by an indenter. The maximun Vickers hardness and fracture toughness were determined to be 12 GPa and 2.8 MPa m0.5, respectively.