Microstructure and mechanical properties of WC–40vol%Al2O3 composites hot pressed with MgO and CeO2 additives

Effects of trace amount of MgO and CeO2 additives on the microstructure and mechanical properties of the WC–40 vol%Al2O3 composites prepared by hot pressing were investigated. The results showed that both the WC–Al2O3 composites doped with 0.1 wt%MgO and 0.1 wt%CeO2 separately, and the WC–Al2O3 composites doped with 0.05 wt%MgO and 0.05 wt%CeO2 together, possessed the refined microstructure and enhanced mechanical properties compared with that of the undoped WC–Al2O3 composites. Trace MgO mainly acted as an effective grain growth inhibitor for the WC–Al2O3 composites and trace CeO2 suppressed the decarburization of WC, promoted the microstructural refinement and improved the interface coherence of the WC matrix and Al2O3. When 0.05 wt%MgO and 0.05 wt%CeO2 were added to the WC–Al2O3 composites, the synergistic effect of MgO and CeO2 resulted in the achievement of a relative density of 99.04% with an excellent Vickers hardness of 18.18 GPa, combining a fracture toughness of 10.14 MPa m1/2 with an acceptable flexural strength of 1158.38 MPa.