Effect of Ni and Mo contents on microstructure, magnetic and mechanical properties of Ti(C, N)-based cermets

Ti(C,N)-based cermets were prepared by vacuum sintering. The effect of Ni and Mo contents on microstructure, magnetic and mechanical properties of cermets were investigated using XRD, SEM, EDS, and VSM. The results showed that the proportion of ceramic hard phase decreased gradually, and the core-rim structure became incomplete with Ni content. However, with an increase in Mo content from 6 to 18 wt. %, the thickness of rim phase slightly increased. The complete core-rim structure refined the grain size of cermets, and the particles became the finest when Mo content was about 14 wt. %. The magnetization of cermets increased with Ni content, while their magnetization gradually weakened with Mo content. The deterioration of magnetic properties was caused by the high total content of Mo and Ti alloying elements in the binder phase. Meanwhile, the hardness of cermets decreased, while the TRS initially increased, followed by a gradual decrease with content of Ni. With an increase in Mo content, the hardness and TRS of Ti(C,N)-based cermets increased firstly and then decreased. The fracture toughness of cermets increased with Ni content, while the increasing Mo content reduced the fracture toughness. Due to grain refinement and solid-solution strengthening of the binder phase, the optimal composition of cermet was Ti(C,N)-14Mo-25Ni, whose hardness, TRS, and Kic values were ~90.3 HRA, 2340 MPa and 11.7 MPa·m1/2, respectively.