Properties and microstructure of VC/Cr3C2-doped WC/Co cemented carbides

This paper deals with the effects of codoped VC/Cr3C2 and sintering temperature on the magnetic and mechanical properties of ultra-fine grained WC-12%Co alloys. Results show that the synergistic action of doped VC/Cr3C2 in optimal proportion enhances both the hardness and transverse rupture strength (TRS) of the alloys, with more homogeneous microstructure. When the alloy is sintered at 1430 degrees C and with 0.5% Cr3C2/0.2% VC, the TRS reaches 3786 Mpa, the hardness is 91.7 HRA and the grain size smaller than 0.6 mu m. The numerical analyses on grain growth during the sintering process show that both VC precipitating on the WC grain boundary and Cr3C2 dissolving in the Co phase decrease the solid/liquid interfacial energy gamma, the process of dissolution and reprecipitation is greatly retarded and the coarsening of WC grains is inhibited.