Development of WC-Ti(C,N)-Cr<sub>3</sub>C<sub>2</sub>-Ni Ultrafine-grained Cemented Carbide and Evaluation of Mechanical Properties

Cemented carbide is a composite material with WC as the main component and Co as the binder phase. Because Co is associated with resource risks, Ni is a candidate as an alternative material. It is known that the strength of WC-Ni cemented carbide can be increased with the decrease of WC particles size. It was clear that adding Ti(C,N) to Ni ultrafine-grained cemented carbide remarkably inhibited the growth of WC particles due to the Ti(C,N) pinning effect. Additionally, optimizing the carbon content and Cr₃C₂ content made the microstructure of WC-Ti(C,N)-Cr₃C₂-Ni ultrafine-grained cemented carbide more uniform, and the bending strength reached 4.3 GPa. Furthermore, when the defects were observed after the tensile test, it was found that the tensile strength increased as the defect size decreased. This was the same as for WC-Co binder ultrafine-grained cemented carbide. In other words, it was found that further increment in strength can be achieved by making the microstructure of WC-Ni ultrafine-grained cemented carbide more uniform and reducing the defect size. These results suggest that WC-Ni binder ultrafine-grained cemented carbide could replace WC-Co binder ultrafine-grained cemented carbide.