Synthesis and characterization of Mo@Ni core-shell composite powder-reinforced (W,Ti)C-based cermet

Abstract

To solve the problem of an insufficient solid solution of the metal bonding phase due to the excessively fast sintering rate when preparing cermet by spark plasma sintering (SPS), a Ni-coated Mo (Mo@Ni) composite powder with a uniform morphology and controllable content ratio was prepared by a heterogeneous nucleation-thermal reduction method. Mo@Ni powder with a sea urchin-like structure was then used to prepare (W,Ti)C/Mo@Ni/Co cermet. The results showed that the optimal sintering temperature of (W,Ti)C-based cermet with Mo@Ni was 50 °C lower than that of (W,Ti)C-based cermet with Ni and Mo. The lower sintering temperature inhibited the growth of matrix grains and improved the flexural strength of (W,Ti)C-based cermet. The addition of Mo@Ni also changed the crack propagation mechanism of (W,Ti)C-based cermet, introduced a variety of toughening mechanisms, and improved the fracture toughness. The topotaxy orientation intergrowth structure formed at the grain boundary is similar to the "fence" effect, which is the main reason for the improvement of mechanical properties.