3D phase field modeling of the morphology of WC grains in WC-Co alloys: The role of interface anisotropy

Understanding the morphological evolution of tungsten carbides (WC) grains is one of a few key factors to control the mechanical properties of the cemented carbides such as wear resistance and toughness. In this work, the three-dimensional (3D) equilibrium morphology of faceted WC grains in WC-Co system was prospected by means of phase-field simulations with parameters adjusted on ab-initio calculations. To model faceted grain surfaces, a specific class of high anisotropy functions harnessing the vertex vectors of the corresponding Wulff shape construction was implemented. As a result, both truncated trigonal prism in C-poor alloys, and trigonal prism in C-rich alloys in WC-25%Co system morphologies could be reproduced, depending on the magnitude of the anisotropy. Phase-field simulations show an excellent quantitative agreement with the present scanning electron microscopy (SEM) observations to representatively sintered WC-Co alloys. This approach paves a new way to model the morphology of high anisotropy grains.