Modulating WC Grain Shape to Enhance Tensile Strength of Cemented Carbides

As a typical brittle ceramic-based composite material, cemented carbides generally have very low tensile strength. Herein, a new approach is proposed to increase tensile strength of WC-Co cemented carbides by forming plate-like WC grains. Tailoring the WC grain morphology and its shape factor is achieved by varying the initial composition of the powders for sintering the cemented carbide. By optimizing the aspect ratio (AR) of the plate-like WC grains, the hardness and fracture toughness are simultaneously increased for the cemented carbide. The microscale stress and strain distributions are further analyzed, which reveal that under tensile loading, the stress concentration and strain localization in the Co and WC phases of the cemented carbides with plate-like WC grains are significantly lower than those in the counterpart with equiaxed WC grains. This inhibits the nucleation of microcracks and enhances the tensile strength of the cemented carbide. As a result, the tensile strength of the cemented carbide with plate-like WC grains at an appropriate AR is increased by 39.2% compared with that with equiaxed WC grains. Herein, a new strategy and an effective method are provided for the development of cemented carbides with high tensile strength.