Enhancing the Corrosion Resistance of AlCoCrFeNi High-Entropy Alloy Coatings via TiO2 Doping

This study investigated the corrosion resistance of laser-cladded AlCoCrFeNi high-entropy alloy coatings with varying TiO2 content (0 wt.%, 0.5 wt.%, 1.0 wt.%, and 1.5 wt.%) in 3.5 wt.% NaCl solution. Optimal cladding parameters (1500 W, 40 mm/s, 11.9 g/min) were determined via orthogonal experiments. TiO2 promoted Ti-rich BCC2-phase precipitation, increased corrosion potential (from −1.4185 V to −0.6841 V), decreased corrosion current density (from 2.33 × 10−4 to 2.28 × 10−6 A/cm2), and enhanced charge-transfer resistance. XPS analysis demonstrated that TiO2 promoted the enrichment of FeO, Cr2O3, and TiO2 components in the passive film while reducing the Al2O3 fraction, leading to the formation of a dense and stable composite passive film that effectively inhibited chloride ion attack. In summary, an appropriate amount of TiO2 doping significantly enhances the corrosion resistance of laser-cladded AlCoCrFeNi HEA coatings, with the 1.5 wt.% addition being the best-performing among the investigated compositions.