Mechanism of the effects of TaC and Cr3C2 on property of WC-Co cemented carbides

The effects of TaC and Cr3C2 on the properties and microstructures of WC-Co alloys are explored. It is shown that small additions of TaC (2wt%) and Cr3C2 (0.44wt%) to the alloy can result in a refinement of the WC grain size, lowering of the WC-WC contiguity and the mean free path of the gamma-phase, but a decrease of the strength-toughness; Cr3C2 can enhance the discontinuous growth of the WC grain size in the WC-Co alloy; the TaC-WC solid solution is less alkali-proof; the brittle fracture of WC-WC boundaries increases and TaC-WC grains tend to cleavage fracture. Controlling the additive amount of TaC and Cr3C2 and ensuring perfect carburization of WC-Cr3C2 as well as adding simultaneously TaC and Cr3C2 in production are of great importance to improving the properties of WC-Co alloys.