Coarse-Grained W _p C-Fe Hardmetals with High Hardness Fabricated by Direct Current Arc In Situ Metallurgy

Coarse-grained W _p C-Fe (P = 1,2) hardmetals were fabricated with tungsten and graphite powders by the direct current arc in situ metallurgy technique. Investigations on the microstructures, morphology evolution, and performance for the resultant materials were also carried out. It is found that with decreasing the applied current, the content of W₂C decreases, but the content and grain size of WC increase. The largest WC grain can reach around 150 μm. The shape of WC changes from hexangular prism to truncated triangle prism, and ultimately transforms into triangular prism due to the different growth rates of the prismatic planes. Furthermore, a layer by layer growth mode of the WC was observed. The performance tests indicate that the average microhardnesses of the WC and W₂C are 2559 and 1916 HV_0.2, respectively. For the WC grain, the microhardness of 2761 HV_0.2 of the triangular basal plane is much higher than the 2357 HV_0.2 of the prismatic plane.