VC/NbC Content Effects on the Microstructure and Performance of Ti-Containing Tungsten-Cobalt Cemented Carbide

When preparing tungsten-cobalt gradient alloy under nitriding conditions, TiC becomes a very important additive because it can effectively promote the formation of gradient structure. However, doping TiC often causes a large number of defects such as holes, cracks, and impurity segregation in the tungsten-cobalt cemented carbide matrix. The paper is mainly studied the improvement of microstructure and mechanical properties of Ti-containing cemented carbide by doping appropriate amount of NbC or VC. The results show that: doping with NbC or VC can refine the grains of the hard phase, effectively control the microstructure and mechanical properties of the alloy, significantly improve its compactness, and increase the hardness and transverse fracture strength of the alloy. However, the fracture toughness is reduced. When the doping amount is less than 0.6% (mass fraction), VC effects on improving the hardness and transverse fracture strength more obviously than NbC; when the doping amount is equal to 0.6% (mass fraction), the difference between VC and NbC in improving the transverse rupture strength is not significant. Comparing the two additive contents studied in this paper, when the VC content is 0.6% (mass fraction), the performance of cemented carbide is better, with a hardness of 1836 HV30kgf, a fracture toughness of 8.85 MPa·m 1/2 , and a transverse fracture strength of 1888 MPa.