Influences of Ni/Cu/Cr3C2 composite additive on microstructure and properties of WC–10Co fine grained hardmetal

Abstract

Aiming to save the high-priced Co resource, Ni, Cu and Cr₃C₂ were simultaneously used to modify WC–10Co fine grained hardmetal, and the effects of sintering temperature on microstructure, mechanical properties were investigated. The combined introduction of Cu/Cr₃C₂ can significantly inhibit the growth of WC grains caused by Ni. When sintered at 1420 °C, the hardness, strength and fracture toughness of WC–0.5Cr₃C₂–(5.4Co3.6Ni1Cu) alloy reach to 1652 HV30, 3301 MPa and 12.01 MPa·m^1/2, respectively, which are higher than those of WC–10Co alloy (1601 HV30, 3193 MPa and 11.75 MPa·m^1/2). In term of corrosion resistance, Ni and Cr₃C₂ can eliminate the adverse effect caused by Cu, as evidenced by the decreased passivation current density (I_pp) and the increased charge-transfer resistance (R_ct). In this regard, Ni/Cu/Cr₃C₂ composite additive would be an effective method to conduct the partial replacement of Co by other low-priced metals without sacrificing the mechanical properties and the corrosion resistance of WC–Co hardmetal.