Nanocrystalline (Ti,Mo,W,Nb,Zr,Ta)(CN) powders were prepared via the carbothermal reduction of a high–energy ball–milled mixture of oxides and graphite. It was observed that the growth of stabilized (Ti,Mo,W,Nb,Zr,Ta)(CN) was suppressed effectively during liquid–phase sintering while maintaining the grain size on an ultrafine scale (below 300 nm). The hardness (max. 16.4 GPa) of the (Ti,Mo,W,Nb,Zr,Ta)(CN)–Ni composites prepared using the stabilized (Ti,Mo,W,Nb,Zr,Ta)(CN) was superior to that (max. 13.2 GPa) of the conventional Ti(CN)–Mo2C–WC–Nb(CN)–Zr(CN)–TaC–Ni composite. Most of the fractures occurred along the interfaces between the (Ti,Mo,W,Nb,Zr,Ta)(CN) and Ni in the (Ti,Mo,W,Nb,Zr,Ta)(CN)–Ni composites, whereas transgranular fractures primarily arise in the conventional Ti(CN)–Mo2C–WC–Nb(CN)–Zr(CN)–TaC–Ni composite during failure.
