Hot-pressing of (Ti, Mt)(C, N)–Co–Mo2C (Mt = Ta, Nb) powdered cermets synthesized by a mechanically induced self-sustaining reaction

• Hot-pressing effects on properties of (Ti, Mt)(C, N)–Co–Mo2C cermets were studied.
• Ceramic phases of cermets consisted of complex solid solution (CSS) carbonitrides.
• Binder phases were formed for Ti–Mt–Co intermetallic (Mt = nothing, Nb, Ta or Mo).
• The addition of Ta, Nb and/or Mo (as Mo2C) hindered the CSS carbonitride growth.
• The presence of Ta, Nb and/or Mo in the Ti–Co intermetallic increased brittleness.

A mechanically induced self-sustaining reaction (MSR) has been successfully employed for manufacturing powdered cermets based on Ti, Ti–Ta and Ti–Nb carbonitrides using Co as the binder phase and Mo2C as the sintering additive. The powders were sintered by hot-pressing, and complete chemical, microstructural and mechanical characterizations were performed on the densified cermets. When elemental Ta, Nb and/or Mo2C were added to the initial raw mixture submitted to the MSR process, smaller ceramic grains were observed after sintering, which suggested that ceramic particle growth was hindered by the presence of Ta, Nb and/or Mo in the host titanium carbonitride structure. Nanoindentation measurements enabled the determination of the hardness of the ceramic and binder phases, and values in the range of 26–29 GPa and 14–16 GPa were found, respectively. The high hardness values of the binder were related to the formation of intermetallic phases.