Investigation of ultrafine WC-Co-Fe-Ni-Cr3C2 cemented carbide microstructure and properties based on phase diagram thermodynamics

In this work, different Fe/Ni ratios with constant Co content were prepared to explore microstructure and properties of ultrafine WC-10 wt.%(Co-Fe-Ni)-Cr3C2 cemented carbides. The increase in Fe content in binder has difficulty in controlling carbon content. Therefore, the carbon window was determined by phase diagram to prepare carbon-balanced cemented carbides. The increase in Fe/Ni ratio in the binder deteriorates the uniformity of the binder phase distribution and refines the WC and binder phase grains by affecting the solubility of WC in binder and the wettability of the binder. Grain size, microstructural irregularities and solid solution strengthening of binder phase affect the mechanical properties of cemented carbides. The relative density of cemented carbide with Fe/Ni = 30:70 in the binder is 99.8 % and the transverse fracture strength is 2449 MPa maximum, but the fracture toughness is slightly low. Because of the passivation characteristics of Ni, the alloy with Fe/Ni = 0:100 in the binder has better resistance to corrosion resistance.