Effect of varying carbon content on microstructure and mechanical properties of (Ti,Ta,Nb,Zr,Mo)C-Co high-entropy ceramic based cermets

The effects of carbon content on microstructure and mechanical properties of the (TiTaNbZrMo)C-Co cermets were investigated in details. Uniform high-entropy carbide powders with different carbon contents were obtained through carbothermal reduction and mixed with a Co binder phase via ball milling for fabricating cermets at the elevated temperature. The increased carbon content makes the hardness of cermets initially rose and then decreased, while the fracture toughness demonstrates an overall decline. Among all high-entropy ceramic based cermets, (TiTaNbZrMo)C0.9-Co cermet (C1) exhibited the optimal combination of hardness and fracture toughness properties, with a Vickers hardness (HV30) of 15.83 GPa and a fracture toughness of 7.74 MPa m1/2. Furthermore, the presence of graphite phases accompanied by the excess carbon content could enhance the wear resistance of cermets. (Ti,Ta,Nb,Zr,Mo)C-Co high-entropy ceramic based cermets have potential applications in the fields of cutting tools and wear-resistant components.