Synthesis of WC-Co composite powders with two-step carbonization and sintering performance study

In this study, WC-Co composite powder was synthesized by two-step carbonization method using W, Co and C as raw materials. X-ray diffraction (XRD) showed that the eta phase (Co6W6C) was kept at 1100 degrees C for 1 h under vacuum, and it could be completely carbonized into WC-Co composite powders. The surface morphology of WC Co composite powders was analyzed by scanning electron microscope (SEM). The effects of eta phase and second phase (W phase) on WC morphology and Co phase distribution were investigated. Electron backscattered diffraction (EBSD) was used to analyze WC-10 wt% Co cemented carbide particle distribution. Comparison of transverse rupture strength, hardness and fracture toughness of two kinds of WC-10 wt% Co cemented carbides synthesized by WC-Co composite powders + WC and WC + Co respectively, the cemented carbide of composite powders + WC increases the fracture toughness from 11.4 +/- 0.3 MPa.m(1/2) to 12.4 +/- 0.3 MPa.m(1/2).