The Tungsten Carbide Involving the Nano Metal Cobalt Domains Synthesized by Carburizing the Cobalt Supersaturated‐Tungsten Powder with CO Gas

The WC involving the nano metal cobalt domains has been prepared by a gas‐solid reaction between the cobalt nonequilibrium supersaturated‐tungsten powder and carbon mono‐oxide gas ( CO ). The metal Co domains formed in the WC were found to be spherical with a diameter of approximately 60 nm by observing the microstructure with a high‐resolution transmission electron microscope ( HRTEM ). The 88.36 mass% WC – 11.64 mass% Co hard metal was prepared by liquid‐phase sintering at 1623 K from the powder compact which was mixture of the WC involving the Co domains and the cobalt powder as binder phase. A nano‐scale fine structure composed of the WC with average diameter, d Av , of approximately 500 nm was obtained. Its Vickers hardness was found to be Hv 1663 ± 43, being nearly equal to the 95.5 mass% WC –4.5 mass% Co with 1–2 μm WC grains. That is, reduction of 7 mass% WC was accomplished. The WC involving the Co domains is expected to be used as raw materials to form the nano‐scale microstructure in the hard metals, resulting in reduction in W components.