Preparation, microstructure, and mechanical properties of ultrafine-grained WC-Cr2(C,N)-Co cemented carbides

The ultrafine-grained cemented carbide was obtained through spark plasma sintering of WC-Cr₂(C,N)-Co nanocomposite powders. The densification mechanism, microstructure, and mechanical properties of the cemented carbide under different sintering temperatures and holding times were investigated. As the sintering temperature increases, the grain size undergoes a gradual increase through the merging of adjacent small WC grains. There is an initial increase, followed by a gradual decrease, in fracture toughness, and a continuous increase in hardness. Cr₂(C,N) enhances the fracture toughness of cemented carbide. WC-Cr₂(C,N)-Co cemented carbide demonstrates excellent mechanical properties, with a grain size of ∼0.445 μm, a hardness of 1842 HV₃₀, and a fracture toughness of 11.41 MPa m^1/2, achieved through sintering at 1200 °C for 5 min. This study provides a novel approach and strategy for the preparation of high-performance cemented carbide.