Experimental and theoretical studies on the elasticity of tungsten to 13 GPa

Abstract

Compressional (VP) and shear wave (VS) velocities of polycrystalline tungsten have been measured up to ∼13 GPa at room temperature using ultrasonic interferometry in a multi-anvil apparatus. Using finite strain equation of state approaches, the elastic bulk and shear moduli and their pressure dependences are derived yielding KS0=325.9±4.8 GPa, G0=164.1±2.5 GPa, KS0′=3.65±0.05, and G0′=1.28±0.02. On the basis of the current experimental data, the high-pressure behavior of Young's modulus, Poisson's ratio, and ductility/brittleness for tungsten are also investigated. Complementary to the experimental data, the single crystal elastic constants, as well as the elastic anisotropy of tungsten are computed using density functional theory (DFT). The Voigt-Reuss-Hill average of the bulk and shear moduli calculated using the single crystal elastic constants from DFT are found comparable to the current experimental results within about 5%. The present study offers a dataset for the elasticity of polycrystalline bcc tungsten to a maximum pressure more than 25-fold higher than other previous ultrasonic studies, which can further our understanding about the elastic, mechanical, and electronic properties of tungsten under extreme conditions as well as thermodynamic modelling of its alloys.