Influence of sintering parameters on the grain growth and mechanical properties of Ti(C,N)-based cermets prepared via mechanical activation and in-situ carbothermal reduction

Series of new type (Ti,Mo)(C,N)-based cermets sintered at different final sintering temperatures were prepared by the mechanical activation and in-situ carbothermal reduction method in vacuum. The grain growth behavior of the complete solid solution cermets was firstly studied by prolonging the holding time at 1400 degrees C by using XRD, SEM, and TEM. Results indicated that the thermodynamic three-dimensional equilibrium morphology of the hard-phase particles were {111}-faceted and round-edged octahedron, whose growth mechanism were predominated by the two-dimensional nucleation that controlled by the diffusion of the dissolved alloying elements in the binder along the close-packed direction. The microstructure and mechanical properties of the cermets were also studied. The results indicated that either too low or too high sintering temperature could deteriorate the homogeneity and porosity of the cermets. Only when the sintering temperature was 1400 degrees C, the optimum TRS, hardness, and fracture toughness of the cermets were 2134 +/- 30 MPa, 88.0 +/- 0.3 HRA, and 20.1 +/- 0.3 MPa.m(1/2), respectively.