Mechanical and Cutting Properties of New Ultrafine-grained Cemented Carbide of WC-Ti(C,N)-Cr<sub>3</sub>C<sub>2</sub>-Co

WC-Co ultrafine cemented carbides added with Ti(C,N) particles of different sizes were fabricated by liquid-phase sintering. The microstructures of these alloys were investigated and compared with those of other carbides. Fine Ti(C,N) addition inhibited the growth of WC grains to almost the same level as Cr3C2 addition. The mechanism underlying the grain growth inhibition by Ti(C,N) particles was the pinning effect (Zener) of the second-phase particles, which was different from the reported mechanism of VC and Cr3C2 addition. Adding Cr3C2 to this alloy resulted in an extremely high strength with an average of 4.7 GPa and a maximum of 5.1 GPa, the world’s highest level. When applied to a cutting tool, these materials demonstrated excellent cutting life. Moreover, novel applications can be expected to take advantage of these properties.