Tuning microstructure for superb mechanical properties in a Ti(C,N)-(WMoTaNbTi)C-Ni/Co cermets via change sintering temperature

Recently, there has been a lot of research focused on high-entropy ceramics (HECs), which are rarely reported as an additional phase of cermets. In this study, HECs nanopowders were prepared by mechanical alloying and used as an additive phase to successfully prepare cermet materials by SPS technology. The microstructure and mechanical properties of cermets were studied by XRD, BSE, TEM, microhardness tester, mechanical universal testing machine and indentation method. The findings demonstrate the production of an ultra-fine rock salt structure (WMoTaNbTi)C HECs with a homogeneous elemental distribution. With the increase of sintering temperature, the relative density of cermets increases steadily. At 1350 °C, the microstructure exhibits a simple combination of the ceramic phase; at 1450 °C, the majority of the core-rim structure is present; and at 1550 °C, there are more coreless gray particles. The comprehensive mechanical properties of cermets are the best when sintered at 1550 °C. The Vickers hardness is 1792.5 HV10, the bending strength is 1305.2 MPa, and the fracture toughness is 9.7 MPa m ^-1/2. The strengthening of fine particles, the toughening of coarse particles, crack deflection, crack bridging and other crack energy dissipation mechanisms are mainly the strengthening and toughening mechanisms of cermets sintered at 1550 °C.