Effect of Mo addition on microstructure and mechanical properties of (Ti,W)C solid solution based cermets

• (Ti,W)C–Mo–Ni cermets were prepared with a pre-alloyed (Ti,W)C solid solution as hard phase.
• The effect of Mo content on the microstructure and mechanical properties of (Ti,W)C -based cermets was investigated.
• The (Ti,W)C phase was transformed into (Ti,W,Mo)C phase after sintered at 1415°C for 1h when Mo was added.
• The core/rim structure was different from TiC- and Ti(C,N)-based cermets and the formation mechanism was discussed.

(Ti,W)C solid solution was synthesized by milling a mixture of C and oxides and then reducing it at 1350 °C for 2 h. The microstructure and mechanical properties of (Ti,W)C solid solution based cermets with various Mo additions were systemically studied. The dark core–gray rim carbide grains and/or gray carbide grains embedded in black Ni based binder phase were observed. The grain size of the cermets decreased with increasing Mo addition, while excessive Mo addition would result in agglomeration and inhomogeneity of the grains. The dark core was transformed from (Ti,W)C into (Ti,W,Mo)C and Mo concentration in the dark core increased with increasing Mo content. The fracture toughness of the cermets decreased with the increase of Mo content, while the hardness and TRS reached a peak value at 10 wt.% and 15 wt.% Mo additions respectively, and declined with the further increase of Mo content.