Study of the compression behavior and elastic properties of HfB2 ceramics using experimental method and first-principles calculations

In-situ high pressure synchrotron angle-dispersive x-ray diffraction (AXRD) studies have been performed for HfB2, an ultra high temperature refractory alloy with AlB2 structure, by using a diamond anvil cell (DAC) at room temperature. The mechanical constants (bulk modulus K, shear modulus G, Young's modulus E, Poisson's ratio nu, density rho, and Debye temperatures Theta(D)) of bulk HfB2 are measured by ultrasound experiments at room temperature. Furthermore, the compression behavior and elastic properties of HfB2 under pressure are investigated using density functional theory. The experimental results are in good agreement with the theoretical calculations. The pressure dependence of mechanical constants and elastic anisotropy of HfB2 are discussed. The experimental data and theoretical calculations results show that HfB2 has a distinct anisotropic compression behavior along the a- and c-axes, and the anisotropy increases as the pressure is increasing. These markedly elastic properties are attributes to the strongly directional bonding between Hf and B atoms. (C) 2019 Elsevier B.V. All rights reserved.