Effect of nitrogen content on microstructures and mechanical properties of Ti(C, N)-based cermets

•The mechanical property was related to the morphology.•Nitrogen influences the morphology and the grain size of sintered cermets.•The hardness increased with the increase of the [N]/([C] + [N]) ratio.•The peak TRS appeared in cermet with the smallest grain size.•The peak KIC appeared in cermet with the medium grain size.

Ti(C, N)-based cermets with different [N]/([C] + [N]) ratios were prepared by vacuum sintering. The mechanical properties, such as the hardness, the transverse rupture strength TRS and the fracture toughness KIC, were related to the nitrogen contents and the morphology. The results indicate that the [N]/([C] + [N]) ratio in the carbonitride raw powders influences the morphology, the grain size and the compositions of the ceramic and the binder phases. The finest grains are found for the cermet with the [N]/([C] + [N]) ratio of 40 at.%. The hardness slightly increases with the nitrogen content. The peak TRS appears in the cermet with the [N]/([C] + [N]) ratio of 40 at.% while the peak KIC appears in the cermet with the [N]/([C] + [N]) ratio of 30 at.%, which are characterized by the smallest grain size and the medium grain size, respectively.