Microstructure and Properties of Ti(C,N)-Based Cermets with Al(x)CoCrFeNiTi Binder

Al(x)CoCrFeNiTi (x = 0.1, 0.3, 0.6, 1) powders were prepared via mechanical alloying and were used as binders for SPS-produced Ti(C,N)-based cermets. The effects of AlxCoCrFeNiTi binder on phase composition, morphology, room-temperature mechanical properties, and oxidation resistance of cermets were studied. The research showed that cermets with Al(x)CoCrFeNiTi binders exhibited a more homogeneous core–rim structure than cermets with cobalt binders. The Vickers hardness and fracture toughness of cermets with Al(x)CoCrFeNiTi binders increased with the aluminum molar ratio due to the grain refinement and solid solution strengthening effect of carbonitrides. After static oxidation at 1000 °C, the mass gain of the cermets with Al(x)CoCrFeNiTi binders changed according to a quasi-parabolic law, and the lowest mass gain was obtained in the cermet with Al(0.6)CoCrFeNiTi binder. The oxidation kinetics curve of the benchmark cermet with cobalt followed a linear law. The oxidation product of Ti(C,N)-based cermet with cobalt was rich in TiO(2), and the Ti(C,N)-based cermets with Al(x)CoCrFeNiTi binders were transformed into complex oxides, such as NiMoO(4), NiWO(4), FeMoO(4), Fe(3)Ti(3)O(9), and Ni(3)TiO(7). The oxide layer on the cermet with Al(0.6)CoCrFeNiTi appeared to be dense and protective, which inhibited the diffusion of oxygen into the cermet and improved the oxidation resistance of the final product.