Corrosion Behavior and Comprehensive Evaluation of Al0.8CrFeCoNiCu0.5B0.1 High-Entropy Alloy in 3.5% NaCl Solution

Abstract

In this study, Al0.8CrFeCoNiCu0.5B0.1 high-entropy alloy coating was prepared on the surface of 5083 aluminum alloy using laser cladding technology. The corrosion behavior of the coating and substrate in 3.5% NaCl solution was analyzed using experimental methods, including polarization curves and electrochemical impedance spectroscopy. The corrosion current density of Al0.8CrFeCoNiCu0.5B0.1 coating is 2.04 × 10−7 A/cm 2. The passivation range width reaches 2.771 V, and these polarization test results are superior to the substrate. The Al0.8CrFeCoNiCu0.5B0.1 coating exhibited selective corrosion behavior, with the Cu-rich FCC1 phase and Cr-poor phase being susceptible to corrosion, leading to localized pitting and intergranular corrosion traces, but the corrosion did not spread extensively. The intergranular distribution of Cu is the main reason for the intergranular corrosion trace features. In contrast, the substrate exhibited overall corrosion. The Nyquist plot of the Al0.8CrFeCoNiCu0.5B0.1 coating consisted of a single capacitive semicircle arc in the high-frequency region with a larger radius than the substrate. In conclusion, using the Al0.8CrFeCoNiCu0.5B0.1 high-entropy alloy as a coating can significantly improve the corrosion resistance of the 5083 aluminum alloy substrate.