Radial X-Ray Diffraction Study of Static Strength of Tantalum to 80 GPa

Abstract

We study the strength and texture of tantalum (Ta) under uniaxial compression up to 80 GPa using an angle-dispersive radial x-ray diffraction technique together with the lattice strain theory in a diamond anvil cell at ambient temperature. The ratio of differential stress to shear modulus (t/G) is found to remain constant above ∼60 GPa, indicating that the Ta starts to experience macro yield with plastic deformation at this pressure. Combined with independent constraints on the high-pressure shear modulus, we find that the Ta sample could support a differential stress of ∼4.67 GPa when it starts to yield with plastic deformation at ∼60 GPa under uniaxial compression. The differential stress in Ta ranges from 0.216 GPa to 4.67 GPa with pressure increasing from 1 GPa to 60 GPa and can be expressed as t = 0.199(33) + 0.075(1)P, where P is the pressure in GPa. A maximum differential stress as high as ∼5.37 GPa can be supported by Ta at the high pressure of ∼80 GPa. In addition, we investigate the texture of Ta under nonhydrostatic compression to 80 GPa using the software package material analysis using diffraction. It is proven that the plastic deformation due to stress under high pressures is responsible for the development of texture.