Synergistic strengthening and toughening of oscillatory pressure sintered WC-ZrO2-Al2O3 ceramics

WC-ZrO2-Al2O3 ceramics with high performance were prepared by oscillatory pressure sintering, and their densification behavior, microstructure and mechanical properties were investigated. The results showed that addition of ZrO2-Al2O3 composite powder can reduce the sintering temperature (from 1900 ℃ to 1760 ℃) and promote densification of the ceramics. When the ZrO2-Al2O3 composite powder content was 8 wt%, it exhibited the best mechanical properties including Vickers hardness of 24.95 GPa, fracture toughness of 7.74 MPa·m1/2 and flexural strength of 1329 MPa. The main strengthening and toughening mechanisms included the phase transformation of zirconia, crack deflection, crack bridging and the presence of many dislocation defects. Also, the formation of well-matched coherent interfaces of WC/ZrO2 and WC/Al2O3 contributed to a synergistic improvement in strength and toughness of WC-ZrO2-Al2O3 ceramics. •Addition of ZrO2-Al2O3 composite powder enhanced the denseness of WC ceramics and inhibited the growth of WC grains.•High performance WC-ZrO2-Al2O3 ceramics were prepared by oscillatory pressure sintering.•WC-ZrO2-Al2O3 ceramics form dislocation structures with coherent interfaces under oscillatory pressure.