Strength, deformation, and equation of state of tungsten carbide to 66 GPa

Strength, texture, and equation of state of hexagonal tungsten monocarbide (WC) have been determined under quasi-hydrostatic and non-hydrostatic compression to 66 GPa using angle-dispersive X-ray diffraction in the diamond anvil cell. Quasi-hydrostatic compression in a Ne pressure medium demonstrates that nanocrystalline WC is slightly less incompressible than bulk-scale WC, with respective bulk moduli of K 0 = 377 +/- 7 and 397 +/- 7 GPa and pressure derivatives K-0 ' = 3.8 +/- 0.3 and 3.7 +/- 0.3. This decrease in incompressibility with grain size is similar to behavior observed in other ceramics. Under nonhydrostatic compression, WC supports a mean differential stress of -12-15 GPa at plastic yielding, which occurs at-30 GPa. Strength in WC is anisotropic, with the (001) plane supporting 29-42% higher stress than stresses calculated from mean strain. Simulations using an Elasto-ViscoPlastic Self-Consistent model indicate that strength inferred from lattice strain theory may be overestimated due to effects of plastic deformation. Plastic deformation generates a texture maximum near ( 2 over line 110 ) in the compression orientation, initially through prismatic slip on the { 10 (1) over bar 0 }((1) over bar2 (1) over bar 0 ) and { 10 (1) over bar 0 }( 0 0 01 ) slip systems, followed by activation of pyramidal slip on { 10 (1) over bar 1 }((2) over bar 113 ) at similar to 40-50 GPa. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.