Fabrication and performances of WC-Co cemented carbide with a low cobalt content

WC-Co cemented carbides with a low cobalt content (<= 3 wt.%) were successfully manufactured by the powder metallurgy method. The cobalt content is lower than conventional cemented carbide (3-30 wt.%), which makes the prepared alloys possess excellent hardness. The effects of cobalt content on the densification behavior, phase composition, micromorphology, and mechanical performances of cemented carbides were investigated in detail. The results revealed that all the sintered alloys were almost completely consolidated with a relative density of greater than 98.0%. Moreover, abnormal grain growth was observed, and the inhomogeneity of WC grains decreased with the increment in cobalt content. In order to obtain cemented carbides with homogeneous microstructure and outstanding performances, VC was added to inhibit grain growth. Microstructure and performances were significantly affected by the addition of VC. The maximum Vickers hardness of cemented carbides without the addition of vanadium was 2234 HV30, while the fracture toughness was 7.96 MPa center dot m(1/2) after sintering WC-2 wt.%Co. After adding VC, the ultimate hardness and fracture toughness of WC-3 wt.%Co-0.5 wt.%VC alloy could reach 2200 HV30 and 8.61 MPa center dot m(1/2), respectively. In addition, the obvious crack deflexion and transgranular behavior can be noticed, which can prevent the extension of crack and achieve an increase in fracture toughness of cemented carbides.