LAUSR

Grain growth inhibitors can effectively suppress the grain size of tungsten carbide (WC), and consequently improve the hardness and strength of the cemented carbides; however, the toughness, one of the most important properties, usually deteriorates with inhibitors. Here, (Cr,Mo,Ta) 2 (C,N) synthesized by carbothermal reduction–nitridation was used as a novel inhibitor, and its effects on the microstructure and mechanical properties of the cemented carbides were investigated. The results showed that the cemented carbides containing (Cr,Mo,Ta) 2 (C,N) outperformed its counterpart comprising the traditional inhibitors in comprehensive mechanical properties, which was mainly attributed to the better inhibition performance provided by the (Cr,Mo,Ta) 2 (C,N) solid-solution powders. With the content of (Cr,Mo,Ta) 2 (C,N) increasing from 0 wt% to 1.25 wt%, the average grain size of WC in the cemented carbides decreased from 0.85 to 0.60 μm firstly, and then increased to 0.64 μm. With 1.00 wt% (Cr,Mo,Ta) 2 (C,N) addition, the cemented carbides with the best performance of hardness (HV 30 ) of 15.55 GPa, transverse rupture strength of 4272 MPa, fracture toughness of 13.91 MPa·m 1/2 were obtained. The electron backscattered diffraction (EBSD) measurements showed that cemented carbides with (Cr,Mo,Ta) 2 (C,N) processed more amount of Σ2 boundary compared with the other specimens, which contributed to better fracture resistance.