Al/Cu Enhancement in Marine Anti‐Biofouling and Anti‐Biocorrosion Performance of High‐Entropy Alloys

Abstract Antibacterial alloys are designed to mitigate biofouling, which is a strategy for combining the defense and function properties of alloys in complex biological environments. However, the current approaches are unable to overcome the issue of microbiologically influenced corrosion (MIC), because antibacterial performances mostly benefit from the excessive dissolution of antibacterial elements in alloys. Herein, a series of Al x CoCrCuFeNi high‐entropy alloys (molar fractions x = 0, 0.1, 0.3, 0.5) are designed. Benefiting from the rigorous management of Al and Cu components, Al 0.3 HEA achieved a 94.1% anti‐biofilm rate against Pseudomonas aeruginosa and an R p value 20 times higher than that for Al 0 HEA, effectively balancing anti‐biofouling and anti‐MIC properties. Specifically, the Cu element induces cell membrane damage and intracellular reactive oxygen species. Al acts as a stabilizer of the Cu‐enriched phase by decreasing the potential difference between the FeCoCrNi‐phase and the Cu‐enriched‐phase, impeding the excessive dissolution of the Cu‐enriched phase while maintaining excellent anti‐biofouling performance. Additionally, Al enhances the components of Al and Cr oxides in passive films, providing robust defense against corrosive species, and ultimately enhancing the MIC resistance of Al 0.3 HEA. This work presents a new strategy for designing MIC‐resistant materials with broad applications in marine engineering.