Microstructures, properties and in situ preparation of novel VC and Al2O3 co-doped WC-Ni3Al-composites by reactive microwave sintering

Abstract: WC-Ni3Al-based composites are promising candidates for use in titanium alloy processing. However, poor dispersion of the bonding and reinforcing phases in the conventionally prepared WC matrix negatively affects the comprehensive properties of WC-Ni3Al-based composites. Thus, novel VC and Al2O3 co-doped WC-10Ni3Al composites were prepared by in situ reactive microwave sintering; further, the microstructure and mechanical properties were characterized. The effects of in situ VC content on the microstructure and mechanical properties were investigated. The composites with optimal microstructures exhibited excellent comprehensive mechanical properties: bending strength of 2234.9 MPa, Vickers hardness of 1956 MPa, and fracture toughness of 22.6 MPa·m1/2. In addition, the friction coefficient of the prepared composites decreased gradually as the VC content increased to 0.75 wt.%; as the VC content increased further, the friction coefficient increased gradually. The enhanced mechanical properties of the prepared composites may be attributed to the reduced porosity of the cement carbides and uniform refinement of the WC grains. The toughening mechanisms of the cemented carbides were also observed.