LAUSR

Abstract The acceleration effect of cobalt on carburization of tungsten at low temperatures was studied by a series of experiments of W, C and Co reactions and theoretical evaluations. Due to Co addition, the formation temperature of WC was greatly reduced (e.g. a decrease from 1300 °C to 850 °C by addition of 1.0 wt% Co). Below the formation temperature of the ternary phase, the converted fraction of W carburization increases with increased Co. Modeling of reaction kinetics revealed that the process of W carburization is dominated by carbon diffusion, and the reaction rate constant is increased much with the increase of Co. The mechanism was proposed that Co acts as the medium for rapid diffusion of C atoms and promotes W carburization by accelerating reaction diffusion kinetics. The present findings will facilitate to develop methods for synthesis of WC-Co composite powders at low temperatures.