Inverse core–rim microstructure in (Ti,Ta)(C,N)-based cermets developed by a mechanically induced self-sustaining reaction

Cermets with a nominal composition (Ti0.8Ta0.2C0.5N0.5— 20 wt.% Co) were synthesised by a mechanically induced self-sustaining reaction (MSR) process from stoichiometric elemental powder blends. The MSR allowed the production of a complex (Ti,Ta)(C,N) solid solution, which was the raw material used for the sintering process. The pressureless sintering process was performed at temperatures between 1400 °C and 1600 °C in an inert atmosphere. The microstructural characterisation showed a complex microstructure composed of a ceramic phase with an unusual inverse core–rim structure and a Ti–Ta–Co intermetallic phase that acted as the binder.

► (Ti0.8Ta0.2)(C0.5N0.5) solid solution, synthesised by MSR, was employed as the raw ceramic material to fabricate cermets.
► The raw material synthesised by the MSR contained Ti–Ta–Co intermetallic solid solution instead of Co as binder phase.
► Inverse core–rim structure by dissolution/re-precipitation process was confirmed. Rim phase was richer in Ti than the core.