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Abstract (Ti 1-x ,Zr x)(C 0.5 ,N 0.5)-Co cermets doped with various zirconium (x = 0, 0.05, 0.1, 0.15) were fabricated by in-situ carbothermal reduction-nitridation and liquid phase sintering-HIP treatment at 1500 °C. The microstructure, mechanical properties and oxidation resistance of (Ti 1-x ,Zr x)(C 0.5 ,N 0.5)-Co cermets were characterized by scanning electron microscope, X-ray diffraction, mechanical properties tests and high temperature oxidation experiment. The results showed that the existence of zirconium in cermets could refine the hard phase grain and improve the mechanical properties of cermets. The proper zirconium addition promoted the formation of a dense protective layer on the surface of cermets at the high temperature, which might reduce the diffusion rate of the oxygen atom and enhance the oxidation resistance of cermets. Highlights • The (Ti,Zr)(C,N)-Co cermets with the different Zr additions were fabricated. • The addition of extra Zr can inhibit the growth of hard phase particles in the sintering process. • The addition of extra Zr can enhance mechanical properties and oxidation resistance obviously. • The Zr-doped cermets hold great potential in machining and structural applications. [ABSTRACT FROM AUTHOR]

To optimize the mechanical properties of Ti(C,N)-based cermets used as tool materials, the cermets with different Ni–Co binder contents and Co/(Ni + Co) weight ratios were prepared. The effects of metal binder content and Co/(Ni + Co) ratio on the microstructure and mechanical properties of Ti(C,N)-based cermets were investigated by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and measuring the transverse rupture strength (TRS), Vickers hardness ( HV ) and fracture toughness ( K IC ). The experimental results reveal that increasing Ni–Co binder content can increase the thickness of rim phases by improving the solid solution reaction and the wetting of hard phases. The cermets with 25 wt.% binder addition present good comprehensive mechanical properties, which is attributed to the moderate rim phases and uniformly distributed Ti(C,N) grains. The Co/(Ni + Co) weight ratios in binder have a great influence on the grain sizes and microstructure features of Ti(C,N)-based cermets, in virtue of the synergic effects between the wettability of Co and the solubilizing capacity of Ni on hard phases. The cermets with pure Co as binder exhibit optimal mechanical properties with a TRS of 1767 ± 81 MPa, a hardness of 12.26 ± 0.10 GPa and a K IC of 8.40 ± 0.47 MPa m 1/2 , which meet the requirements for tool materials. And the cermets with a Co/(Ni + Co) ratio of 0.2 have the second best mechanical properties with a TRS of 1848 ± 201 MPa, a hardness of 11.12 ± 0.40 GPa and a K IC of 9.43 ± 0.54 MPa m 1/2 , in which the lower hardness can be further improved by optimizing the compositions and sintering process. [ABSTRACT FROM AUTHOR]

A suitable sintering method is important to obtain the Ti(C,N)-based cermets with superior properties. In this paper, Ti(C,N)-based cermets were fabricated by hot-pressing sintering (HP) and conventional pressureless sintering (PLS) technology, respectively, to investigate the influence of different sintering methods on the microstructure and mechanical properties of cermets materials. The microstructure, fracture morphology, indention cracks and phase composition were observed and detected using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The transverse rupture strength (TRS), Vickers hardness ( HV ) and fracture toughness ( K IC ) were also measured. The results reveal that all of the Ti(C,N)-based cermets exhibit core–rim microstructures with black cores, white cores and grey rims embedded into metal binder phases. The grain size of the samples fabricated by HP is much finer and the structure is more compact than those fabricated by PLS, while there exist pores in the HP sintered samples. The sintering process has no influence on the phase composition of cermets, but affects the phase content and crystallinity. The samples fabricated by PLS present higher transverse rupture strength, fracture toughness and density than samples fabricated by HP. However, the HP sintered samples possess a higher hardness. [ABSTRACT FROM AUTHOR]