Phase transformation of nano-grained W(Co, C) composite powder and its phase constitute

Abstract

A new process of WC-Co cemented carbide was developed by using nano-grained W(Co, C) composite powders as raw materials processed by high-energy ball milling. X-ray diffraction(XRD), differential thermal analysis (DTA), thermo-gravimetric (TG) analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy(SEM). The results show that the as-milled powders are transformed into transitional phases W₂C and η (Co₃W₃C or Co₆W₆C) during sintering, and finally transformed into WC and Co phases completely at 1 250 °C for 30 min, and a large number of fibrous WC grains with about 1.2 μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 °C.

Keywords

cemented carbide / phase transformation / high-energy ball milling / fibrous WC grain

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