On the Solubility of Chromium in Cubic Carbides in WC-Co-MC-Systems

The solubility of Cr in cubic carbides in the systems WC-Co-TaC and WC-Co-ZrC has been determined using equilibrium samples. Thermodynamic calculations were used to design the alloys through extrapolations of Gibbs energy expressions. The alloys were designed to have a microstructure containing the following phases: WC, liquid, M7C3, graphite and cubic carbide. The samples were equilibrated at 1410 deg C. The alloys were investigated using scanning electron microscopy and analyzed using energy-dispersive X-ray spectrometry. The present work shows holm'the Cr solubility depends on which cubic carbide former that is present. The WC-Co-Cr-Zr alloy has no detectable amount of Cr in the cubic carbide, whereas the WC-Co-Cr-Ta alloy has 12 % Cr in the cubic carbide.