Effect of nitrogen and secondary carbide on the microstructure and properties of (Ti0.93W0.07)C–Ni cermets

• Solid-solution carbide and carbonitride cermets were prepared.
• Mo2C dissolves readily in (Ti,W)(CN)-Ni, resulting in a fine microstructure.
• The effect of nitrogen is stronger in refining (Ti,W)C than that of a Mo2C addition.
• The hardness of (Ti,W)(CN)-20Ni was 12.7 GPa, increasing to 13.9 GPa with Mo2C.

Solid-solution powders of (Ti0.93W0.07)C and (Ti0.93W0.07)(C0.7N0.3) were synthesized via high-energy ball milling and carbothermal reduction processes. After blending powders with Ni and other carbides, cermets were prepared by a blending and sintering process at 1510 °C for 1 h. We observed a typical core/rim structure consisting of solid solution phases. We also found that secondary carbide and nitrogen have a remarkable influence on the cermet microstructures. Further, with an increase in the Mo2C content, the mechanical properties of these cermets were enhanced significantly; the hardness of carbide and carbonitride cermets increased from 9.3 and 12.7 to 12.9 and 13.9 GPa, respectively. All results are discussed in terms of the thermodynamic stability and dissolution behavior of the constituent carbides and carbonitride.