Ti(C,N)-based cermets with fine grains and uniformly dispersed binders: Effect of the Ni–Co based binders

Abstract

Metallic binder is a key factor affecting the microstructure and mechanical properties of Ti(C,N)-based cermets. To optimize the overall performances, cermets with various weight ratios of Ni/(Co + Ni) ranging from 0 to 1 were fabricated by gas pressure sintering. Microstructure, phase formation, interface structure and related mechanical properties of the sintered cermets were investigated. With the increase of the Ni/(Co + Ni) ratios, the black cores became smaller and grains of Ti(C,N) dispersed uniformly. Compared to the pure Ni or Co, Ni–Co binders accelerated the formation of rim phases, and avoided the nonuniform dispersed binder pools. When the ratio was 0.5, the cermets showed fine grains, uniformly dispersed binders and small lattice misfit of the core-rim interface, exhibiting the optimal mechanical properties, i.e. satisfactory Vickers hardness of 1670 (HV30) Kgf/mm2, bending strength of 1970 MPa and Fracture toughness of 8.94 MPa m0.5. This work sheds light on constructing the relationship between the microstructure, mechanical performance of Ti(C,N)-based cermets and the Ni/Co-based binders.