Strengthening of Micron-sized TiC-Based Cermets with Uniformly Dispersed Ultrafine Ti(C,N) Grains: Microstructure and Mechanical Properties

Micron-sized TiC-based cermets have low density, high hardness and wear resistance, but suffer from the unsatisfactory strength and toughness. Building dual-grained cermet with ultrafine additions to decline the strain stress is an efficient approach. Herein, through integrating the high thermal conductivity and strength of Ti(C,N), micron-sized TiC-based cermets with uniformly dispersed ultrafine Ti(C,N) were prepared by low pressure sintering process, of which the microstructure and mechanical properties was examined by transmission electron microscopy, x-ray diffractometer and scanning electron microscopy. The results show that the ultrafine Ti(C,N) powders content have a significant effect on the microstructure evolution and mechanical properties of TiC-based cermets. When the ultrafine Ti(C,N) powders content is increased from 0 to 40 wt.%, the microstructure is more uniform, and the hardness and density of the alloy increase due to the decreases of the grain size and porosity. When the ultrafine Ti(C,N) content is greater than 40 wt.%, the fine particles in the microstructure increase and the porosity increases. Ultrafine structure determine the intergranular motion, lattice dislocation and lattice compatibility of cermet. When 20 wt.% ultrafine Ti(C,N) was added, the mechanical properties is superior, and the strength and toughness reach 1930 MPa and 8.87 MPam^1/2, respectively.