High-entropy amorphous materials are attracting increasing attention due to their excellent corrosion resistance and radiation tolerance in nuclear environments. In this study, novel Al₂Cr₁₆Fe₅₀V₂₀Ti₁₂ high-entropy alloy (HEA) coatings with thicknesses of 900 nm and 1400 nm were synthesized via magnetron sputtering and systematically evaluated for their structural, electrochemical, and mechanical performance. X-ray diffraction confirmed the amorphous nature of the coatings, while scanning electron microscopy revealed a denser, defect-free, and more uniform morphology in the thicker coating. Electrochemical testing in a 3.5 wt.% NaCl solution demonstrated a tenfold reduction in corrosion current density and nearly a twofold increase in charge transfer resistance for the 1400 nm coating, attributed to its improved passive film stability. Finite element modeling validated the experimental load–displacement behavior and revealed well-confined and uniformly distributed stress and strain fields within the coating. These findings establish the 1400 nm Al₂Cr₁₆Fe₅₀V₂₀Ti₁₂ coating as a promising candidate for protective applications in chloride-rich and radiation-intense nuclear systems.

Non-metallic inclusions are preferential sites for pitting corrosion initiation in austenitic stainless steels. This study investigates the effect of magnesium addition on inclusion evolution and localized corrosion behavior of austenitic stainless steel using SEM–EDS, immersion testing, scanning Kelvin probe force microscopy (SKPFM), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Magnesium addition modifies the inclusion population from coarse (Mn,Al)-O into finer MgO·Al₂O₃ spinel-based inclusions with improved distribution. Immersion testing in FeCl₃–HCl solution reveals delayed inclusion dissolution and reduced localized pitting attack in the Mg-treated steel. SKPFM maps, together with immersion observations, provide qualitative evidence of changes in the local electrochemical contrast between inclusions and the surrounding matrix. Electrochemical measurements in 3.5 wt.% NaCl further demonstrate improved corrosion resistance after Mg addition, as evidenced by an increase in pitting potential from 0.28 V to 0.52 V vs. SCE and charge-transfer resistance. The improved corrosion resistance is associated with inclusion refinement and modification of the local surface-potential distribution, which may influence inclusion-related localized corrosion processes. Overall, Mg microalloying modifies the inclusion characteristics of austenitic stainless steel and enhances its resistance to chloride-induced localized corrosion, demonstrating the potential of inclusion engineering as a strategy for improving stainless-steel corrosion performance.