Effect of Cr-rich precipitates on the wear and corrosion resistance of FeNiCoCr multi-principal element alloy coatings

Abstract Marine engineering structures are simultaneously exposed to chloride-rich corrosive atmospheres and mechanical wear. Although multi-principal element alloy (MPEA) coatings are attractive protective candidates, combining high wear resistance with long-term corrosion stability remains challenging. Here, three non-equiatomic FeNiCoCr MPEA coatings with distinct distributions of Cr-rich precipitates are comparatively investigated by dry sliding tests and 60-day acetic acid salt spray exposure. The Fe 5 Ni 2 Co 2 Cr coating, containing discrete nanoscale Cr-rich precipitates, exhibits the lowest wear rate (approximately 2.0 × 10 −5 mm 3 N −1 m −1 ) and only isolated shallow pits after 60 days, with its surface evolving towards a Cr-rich, Fe-lean near-surface layer. In contrast, an interconnected precipitate network provides brittle intergranular paths for wear-induced delamination and Cr-lean anodic paths for localized corrosion. Controlling precipitate continuity and Cr distribution is therefore an effective microstructural design strategy for durable MPEA coatings in marine environments.