The kinetics of incongruent reduction of tungsten carbide via reaction with a hafnium–copper melt

Abstract The reduction of WC into W by reaction with a Hf–Cu melt has been found to proceed by the formation of layers of W and HfC. The extent of such incongruent WC reduction has been examined after the immersion of dense, polycrystalline WC plates in a vertical orientation in Hf–Cu melts at 1150–1300 °C for 1–24 h. A W layer of uniform thickness formed adjacent to the WC, whereas an irregular, but generally continuous HfC layer formed adjacent to the W layer. The rate of WC reaction was evaluated by measuring the thickness of the W layer as a function of reaction time, temperature and vertical position along the WC surface. Such kinetic data and microstructural analyses indicated that the incongruent reduction of WC in molten Hf–Cu is likely to be controlled by the diffusion of carbon through the W and/or HfC layers.