Corrosion Resistance of WC-based Cemented Carbides with 10 Wt% AlxCrCoCuFeNi High-Entropy Alloy Binders

The corrosion behaviour of WC-based cemented carbides with 10 wt% AlxCoCrCuFeNi (x = 0, 0.5, 1.0, and 1.5) high-entropy alloy (HEA) binders in 3.5 wt% NaCl solution was comparatively investigated by using electro-chemical methods, and the effects of the HEA binder on the corrosion resistance of WC-HEA cemented carbides were studied. Compared with WC-Co, the WC-HEA cemented carbides show significantly better corrosion resistance. During the corrosion process, an electrode reaction occurs between the WC hard phase and the HEA binder phase, and the HEA binder dissolves as an anode. The Cr2O3 and Al2O3 passive films formed on the surface of the HEA binder inhibit the dissolution of the anode, which improves the corrosion resistance of the WC-HEA cemented carbides. The corrosion performance of the HEA binder largely determines the corrosion resistance of the WC-HEA cemented carbides. With increasing Al content of the HEA binder, the formations of a Cu-rich phase with poor corrosion resistance and the Cr2O3 passive film with better protection against corrosion are restrained. Therefore, a strong positive correlation between the corrosion resistance of WC-HEA cemented carbide and the Al content of the HEA binder is not observed.