VC and Cr3C2 doped WC–MgO compacts prepared by hot-pressing sintering

The effects of doping with VC and Cr3C2 (grain growth inhibitors, GGIs) on the microstructural characteristics and mechanical properties of WC–MgO compacts prepared by hot-pressing sintering were investigated. GGIs suppressed the rate of densification during isothermal and non-isothermal sintering, but eventually increased the sintered density with extended holding time. Microstructure observation results revealed that the grain growth of WC was significantly retarded, and the homogeneity of MgO particulate dispersion and particulate/matrix interfacial coherence were improved effectively with the addition of GGIs. Meanwhile, the activation energy for grain growth during isothermal sintering increased from 426.85 to 492.53 kJ/mol, which is consistent with the inhibition mechanism of VC and/or Cr3C2. The mechanical properties (hardness, fracture toughness and flexural strength) of compacts were enhanced by adding 0.25 wt.% VC and 0.25 wt.% Cr3C2.

► We studied the effect of VC and Cr3C2 addition on the sintering of WC–MgO compacts. ► The rate of densification and grain growth were mitigated with the GGI addition. ► An improvement on the mechanical properties of WC–MgO was observed. ► The activation energy for grain growth during isothermal sintering was increased.