Effects of Ni on the microstructures and properties of WC–6Co cemented carbides fabricated by WC–6(Co, Ni) composite powders

Abstract

WC–6(Co, Ni) composite powders with different Co/Ni ratios were fabricated through hydrogen reduction of WC–(Co, Ni)C2O4·2H2O precursor. The effects of Ni on the sintering behavior, microstructures, corrosion resistance and mechanical properties of WC–6(Co, Ni) cemented carbides were investigated using dilatometer, scanning electron microscope, electrochemical test and mechanical properties tests. The results show that the mixing of WC powders and Co–Ni prealloyed powders can be integrated in the preparation of Co–Ni prealloyed powders. The liquid phase temperature and corrosion resistance of WC–6(Co, Ni) cemented carbides increase with the increase of Ni content. When 20wt.% Co is substituted by Ni, the average WC grain size decreases from 1.67μm to 1.48μm, the hardness and the transverse rupture strength increase from 1445HV30, 2182MPa to 1470HV30, 2276MPa, respectively, while the corrosion rate decreases from 176.23×10−2mm/a to 89.94×10−2mm/a. In this case, it is feasible that Co is partly substituted by Ni if the novel WC–6(Co, Ni) composite powders are applied in the preparation of WC–6Co cemented carbides containing Ni.