Effect of ni content on mechanical properties and corrosion resistance of WC-Co-Ni cemented carbides

WC-Co-Ni cemented carbides with 90 wt.% WC and different Co/Ni ratios (WC-(1?x)Co-xNi, where x = 0, 1, 3, 5, 7 and 9 wt.%) were prepared by powder metallurgy method. The aim was to study the microstructure of these carbides, analyse their mechanical properties and investigate their corrosion resistance and thus find the optimal Co/Ni ratio for the fabrication of reliable cutting tools. The results show that with the increase of Ni content, the grain size and inhomogeneity gradually increase. On the other hand, the hardness, wear resistance and flexural strength of WC-Co-Ni cemented carbides decrease. The fracture toughness firstly increases and then decreases while the corrosion resistance is enhanced. The WC-7Co-3Ni specimen had the best comprehensive mechanical properties compared to other composites. This, together with the improved corrosion and damage resistance, confirmed that the WC-7Co-3Ni composite could substantially extend the working life of shield machine tools.