“Regeneration-Repair-Strengthening” mechanism in the oxidation film damage region of copper-nickel alloys under magnetic field effects

Copper-nickel alloy pipes in marine environments are prone to scouring by solid particles, which disrupt the bilayer oxidation film and induce scratches. These scratched regions are more vulnerable to perforation, potentially leading to premature pipe failure. Thus, rapidly repairing the film and restoring its corrosion resistance is a major challenge. This study simulates the "film damage-regeneration" process of copper-nickel alloys in marine environments, researching the regeneration of the film in scratched regions of a 70/30 Cu-Ni alloy in a 3.5 wt% NaCl solution, under both non-magnetic and magnetic field conditions. The results demonstrate that the application of a magnetic field accelerates the regeneration of the film and, through synergistic interactions with the scratched microregions, alters the local pH conditions, suppresses the re-deposition of Cu<2/sup>O, and significantly enhances the enrichment of NiO on the surface of the regenerated film. Ultimately, a unique single-layer film structure with enhanced corrosion resistance is formed. Notably, this single-layer film structure represents the first reported observation in copper-nickel alloy studies. This work offers a novel approach for in-situ copper-nickel alloy pipeline's film repair, with significant implications for extending the lifespan of marine engineering infrastructures.