Effects of partial substitution of copper for cobalt on the microstructure and properties of ultrafine-grained WC-Co cemented carbides

Co-Cu composite powders with different Cu contents were synthesized via an ultra-rapid solution combustion synthesis (SCS) method and WC-10(Co/Cu) cemented carbides with an ultrafine grain size were prepared by microwave sintering the compacts of powder mixes of WC and the Co-Cu composite powders. The effects of Cu addition on the microstructure and properties of the microwave-sintered WC-Co cemented carbides were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), field emission transmission electron microscopy (FE-TEM) and mechanical properties tests. The results showed that the addition of a small amount of Cu instead of Co in the WC-Co cemented carbides enhances the sintering, restrains the WC grain growth and improves the mechanical properties. The average WC grain size decreases as Cu is added, and the grain size distribution narrows. The Rockwell hardness and fracture toughness of the WC-10(Co/Cu) alloys with a 0.5 wt% Cu addition reach 90.7 HRA and 14.3 MPa m−1/2, respectively. In addition, the transverse rupture strength (TRS) reaches 2544.7 MPa with a 1 wt% Cu content. The present results show that Cu-doped WC-Co cemented carbides have excellent comprehensive performances.