Abstract
The synergistic impact of electrochemical corrosion and biological fouling poses a significant challenge to materials in marine environments. High-entropy alloys (HEAs) offer a promising platform for developing multi-functional materials; however, achieving a balance between abiotic corrosion resistance and antibacterial efficacy remains a critical hurdle. Current approaches often fail to overcome microbiologically influenced corrosion (MIC) because antibacterial performance typically relies on the excessive dissolution of active elements, which compromises the alloy's structural integrity.
In this study, a series of AlCrFeNiCux (x = 0, 0.01, 0.05, 0.1, 0.3, 0.5) HEAs were designed to investigate the coupling relationship between Cu-induced microstructural evolution and protective performance. Benefiting from the rigorous management of Al and Cu components, the x = 0.05 alloy achieved an optimal balance: it exhibited the highest abiotic corrosion resistance and a 98.5% anti-biofilm rate against Pseudomonas aeruginosa.
Specifically, the trace addition of Cu induces cell membrane damage and intracellular reactive oxygen species (ROS) in sessile bacteria. Al acts as a stabilizer of the Cu-enriched phase by decreasing the electrochemical potential difference between the constituent phases, thereby impeding excessive dissolution while maintaining high antibacterial efficacy. Furthermore, Al enhances the enrichment of Al and Cr oxides within the passive film, providing a robust defense against corrosive species and significantly boosting MIC resistance. By establishing a comprehensive "Cu content-functional structure-anti-fouling/corrosion" correlation map, this work provides a new strategic framework for designing high-performance MIC-resistant materials for complex marine engineering applications.