Microstructure and Properties of Ti(C,N)-Based Cermets with AlxCoCrFeNiTi Binder

Abstract

AlxCoCrFeNiTi (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 AlxCoCrFeNiTi binders exhibited a more homogeneous core–rim structure than cermets with cobalt binders. The Vickers hardness and fracture toughness of cermets with AlxCoCrFeNiTi 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 AlxCoCrFeNiTi binders changed according to a quasi-parabolic law, and the lowest mass gain was obtained in the cermet with Al0.6CoCrFeNiTi 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 TiO2, and the Ti(C,N)-based cermets with AlxCoCrFeNiTi binders were transformed into complex oxides, such as NiMoO4, NiWO4, FeMoO4, Fe3Ti3O9, and Ni3TiO7. The oxide layer on the cermet with Al0.6CoCrFeNiTi appeared to be dense and protective, which inhibited the diffusion of oxygen into the cermet and improved the oxidation resistance of the final product.