Non hydrostatic Compression behavior of HfB2 to 220 GPa and Determination of Hydrostatic EoS and Shear Strength to 70 GPa.*

Hafnium diboride belongs to the class of high strength transition metal diborides that exhibit high bulk moduli and known for its excellent resistance to thermal degradation in oxidizing environment at high temperatures. In this study, the compression behavior of hafnium diboride was investigated up to 220 GPa under nonhydrostatic conditions at ambient temperature using angle dispersive axial x-ray diffraction (A-XRD) with a diamond anvil cell (DAC). In addition, shear strength of hafnium diboride was measured to 70 GPa using radial x-ray diffraction (R-XRD) technique in DAC. The platinum was employed as an x-ray pressure standard in all measurements. R-XRD combined with lattice strain theory enables the determination of shear strength to high pressure and the determination of hydrostatic strain during compression. The static compression data and mechanical properties of Hafnium Diboride will be compared with the first-principle theoretical calculations.