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Ti-doped WC-Ni3Al cemented carbide was prepared by spark plasma sintering for improving mechanical properties. The effect of different Ti contents on the microstructure and mechanical properties of WC-Ni3Al cemented carbide was investigated. The results show that due to Ti addition, the small amount of Al2O3reactively formed in WC-Ni3Al is smaller and more uniform than the sintered sample without adding Ti. The refinement of Al2O3 and the in-situ (Ti, W) C synergistically enhance the hardness of the WC-Ni3Al cemented carbide. Meanwhile, the fracture toughness is improved because the in-situ (Ti, W)C and WC have a better interface combination, facilitating the bridging and deflection formation of cracks. The WC-Ni3Al cemented carbide with 3% (mass fraction) Ti obtains the optimal mechanical properties, with hardness of (19.29±0.18) GPa and fracture toughness of (13.14±0.24) MPa·m1/2.

In order to reduce the sintering temperature and obtain higher fracture toughness of WC cemented carbides without metallic binder, WC cemented carbide was toughened by MgO and B2O3. Dense WC-MgO-B2O3 bulk materials were prepared at the relative low temperature of 1400℃ via spark plasma sintering(SPS), and the effects of MgO-B2O3 addition on sintering mechanism, microstructure evolution and mechanical properties of WC cemented carbides without metallic binder were studied. The results show that the addition of MgO-B2O3 promotes the sintering densification of WC, and reduces the sintering temperature of WC cemented carbides without metallic binder. With the increase of MgO-B2O3 contents, the morphology of some second phases in the microstructure is gradually transformed from short rod-shaped to long rod-shaped, and then to aggregated block. When MgO-B2O3 content reaches 8% (mass fraction), the bulk material has better fracture toughness of (9.45±0.37) MPa·m1/2, and its hardness is (18.16±0.17) GPa.