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The grain growth retardation mechanism and the effect of cooling rate on VC-doped WC–Co cemented carbides were investigated in this work.WC–30Co and WC–30Co–VC were prepared by powder metallurgy,liquid-phase sintering at 1400 °C and followed by water quenching([150 °C/s) or furnace cooling(*0.083 °C/s).Based on the results of electron probe microanalysis(EPMA),we found that WC concentration in the Co binder was independent of VC doping during liquid-phase sintering,hence barely contributing to the retardation of WC grain growth.In contrast,the(W,V)C_x phase formed at the WC/Co interfaces played a major role in retarding WC grain growth during liquid-phase sintering.The effect of cooling rate on the morphology of(W,V)C_xwas revealed by high-resolution transmission electron microscopy(HRTEM) and energy-dispersive spectroscopy(EDS).In the water-quenched WC–30Co–VC,(W,V)C_xprecipitates were found as thin layers at the WC/Co interfaces.In contrast,both thin layers of similar thickness and nanoparticles of(W,V)C_x were observed in the furnace-cooled counterpart.These observations listed above suggested that thin(W,V)C_xlayers were stable structures effectively suppressing the growth of WC grains and their thickness remained independent of the cooling rate.The(W,V)C_xnanoparticles,however,may be inhibited through rapid cooling,ensuring the VC-doped WC–Co cemented carbides desired toughness.
The grain growth retardation mechanism and the effect of cooling rate on VC-doped WC-Co cemented carbides were investigated in this work. WC-30Co and WC-30Co-VC were prepared by powder metallurgy, liquid-phase sintering at 1400 ° C and Followed by water quenching ([150 ° C / s) or furnace cooling (* 0.083 ° C / s). Based on the results of electron probe microanalysis (EPMA), we found that WC concentration in the Co binder was independent of VC doping During (W, V) C_x phase formed at the major role in retarding WC grain growth during liquid-phase sintering. The effect of cooling rate on the morphology of (W, V) C_xwas revealed by high-resolution transmission electron microscopy (HRTEM) and energy-dispersive spectroscopy (EDS) .In the water- quenched WC- 30Co-VC, ) C_xprecipitates were found as thin layers at the WC / Co interfaces.In contrast, both thin layers of similar thickness and nanoparticles of (W, V) C_x were observed in the furnace-cooled counterpart. These precount listed above suggested that thin (W, V) C_xlayers were stable structures substantially suppressing the growth of WC grains and their thickness remained independent of the cooling rate. (W, V) C_xnanoparticles, however, may be inhibited by rapid cooling, ensuring the VC-doped WC-Coated carbides desired toughness.