Mechanical properties and microstructure of WC-Fe-Ni-Co cemented carbides prepared by vacuum sintering

Abstract

In this work, the effects of both the vacuum sintering temperature and time on microstructure and properties evolution of the WC-Fe-Ni-Co cemented carbides were investigated. And, the alloys with excellent properties were successfully prepared by vacuum sintering. The results show that both the sintering temperature and time are critical factors affecting the porosity, microstructure and mechanical properties of the alloys. There are a large number of pores and inhomogeneous distribution of binder phase in the alloys at lower sintering temperature. When the sintering temperature increases to 1380 °C, the alloys have the least porosity (0.41%), most homogeneous microstructure and best hardness, fracture toughness and transverse rupture strength (TRS). With further raising sintering temperature, the porosity increases while mechanical properties decrease slightly. When the alloy sintered for 30 min, the nearly fully densified alloys are produced, but there are some aggregate binder phases. For a sintering time of 60 min, the binder phase is distributed uniformly and the alloy is of the highest TRS. Meanwhile, with increasing the sintering time, the hardness gradually decreases while the fracture toughness gradually increases. Therefore, the WC-Fe-Ni-Co cemented carbide sintered at 1380 °C for 60 min with fcc binder phase exhibits the optimum mechanical properties.