Low-energy grain boundaries in WC-Co cemented carbides

The influencing factors, distribution characteristics and evolution mechanisms of the typical low-energy grain boundaries in the WC-Co cemented carbides were demonstrated. Based on characterizations from various angles, the correlations of grain shape aspect ratio, WC contiguity and distribution of low-energy grain boundaries were analyzed for cemented carbides with addition of different grain growth inhibitors. It was found that the Sigma 2 grain boundaries have higher fraction in the cemented carbides with stable complexions, finer grain size and larger WC contiguity. The Sigma 13a grain boundaries are likely to form in the cemented carbides with anisotropic surface energy by coalescence of WC platelets with large shape aspect ratio. The results suggest that the fraction and distribution of low-energy grain boundaries in the cemented carbides can be modulated by matching grain growth inhibitor and sintering temperature of the initial WC-Co composite powder. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.