Compressive creep of coarse-grain WC–Co and WC–TaC–Co hardmetals with uniform microstructure comprising rounded WC grains

Abstract The creep process of coarse-grain WC-6%Co hardmetals with uniform microstructure comprising rounded WC grains undoped and doped with 0.2 wt% TaC was studied under uniaxial compressive loads in two temperature ranges of 300–500 K and 600–970 K. The amount of TaC added to WC–Co was below its solubility limit, so that the microstructure of the hardmetal doped with TaC did not contain grains of the second carbide phase (Ta,W)C of the order several microns in size. The creep activation energy in the medium-low temperature range (T = 300 … 500 K) is quite low and lies between 13 kJ/mol and 25 kJ/mol. The activation energy noticeably increases at higher temperatures and varies from 50 kJ/mol to 90 kJ/mol in the temperature range of 600–970 K. As a result of doping the WC-6%Co hardmetal with tantalum carbide the creep resistance significantly increases. In the temperature range of 600–900 K the doping leads to reducing creep rates by a factor of up to nine.