A novel fabrication technique of toughened TiC-based solid solution cermets using mechanochemical synthesis

Abstract

Ceramic–metal composite powders (Ti,M)C-Ni (M = Mo, W and Ta) were prepared from elemental powders using a one-step mechanochemical synthesis method through high-energy ball milling. The microstructure and mechanical properties of the resulting cermets were also investigated. The analytical results revealed that ball milling of Ti-M-C-Ni elemental powders triggered a combustion reaction between Ti and C. The reaction resembled a fast sintering process which facilitated alloy elements atoms dissolve into the newly formed TiC, synthesizing the (Ti,M)C-Ni composite powders. The microstructure of the sintered (Ti,M)C-Ni cermets consisted of the core-rim structure grains and homogenous grains. High-resolution transmission electron microscope analysis results revealed that there was a misorientation between the ceramic phase and the binder phase in the cermets, but the interface between the core and the rim was coherent. The cermets exhibited mechanical properties that were comparable to conventionally produced cermets, particularly in fracture toughness which was as high as 12.45 MPa m1/2. The excellent cohesion between the Ni binder and the (Ti,M)C solid solution and the reduction in the interfacial stress in ceramic grains were believed to be responsible for the enhanced toughening of the cermets.