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<p>304 stainless steel (SS) is prone to localized corrosion in acidic environments, reducing its lifespan and safety. Herein, FeCoNiCrx (<i>x</i> = 1.5, 1.8, 2.1, 2.4) high-entropy alloy (HEA) coatings were applied to 304 SS using <i>in situ</i> laser cladding (LC) to correlate composition with performance. Microstructure and chemistry were analyzed by XRD, OM, SEM and XPS. Corrosion resistance was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The coatings exhibited dual-phase face-centered cubic (FCC) and body-centered cubic (BCC) structures, with BCC content increasing as Cr increased. The Cr1.8 coating demonstrated the best corrosion resistance in 0.1&#xa0;M sulfuric acid (H<sub>2</sub>SO<sub>4</sub>), with polarization resistance (<i>R</i><sub>p</sub>) of 851.1&#xa0;kΩ&#xa0;cm<sup>2</sup> (5.47 times the substrate) and low corrosion current density (<i>I</i><sub>corr</sub>) of 1.173&#xa0;<i>μ</i>A/cm<sup>2</sup>. As Cr content rose (<i>x</i> ≥ 2.1), galvanic coupling between FCC and BCC phases accelerated localized corrosion, weakening oxide formation and reducing resistance in Cr2.1 and Cr2.4 coatings. In 0.5&#xa0;M&#xa0;H<sub>2</sub>SO<sub>4</sub>, Cr2.4 showed superior resistance, with maximum <i>R</i><sub>p</sub> of 1762.4&#xa0;kΩ&#xa0;cm<sup>2</sup> (11.33 times the substrate) and minimum <i>I</i><sub>corr</sub> of 0.288&#xa0;<i>μ</i>A/cm<sup>2</sup>, due to a stable Fe–Cr oxide passive film. This study provides insights for designing HEA coatings with enhanced corrosion resistance.</p>

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Microstructural Evolution and Acid Corrosion Mechanism of Laser-Clad FeCoNiCrx High-Entropy Alloy Coatings

  • 期刊论文

  • 发表日期：

    2026年7月17日

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  • Yongguan Xiao,
  • Peng Xu,
  • Ling Wang,
  • Xingyou Zuo,
  • Chi Pang

摘要

304 stainless steel (SS) is prone to localized corrosion in acidic environments, reducing its lifespan and safety. Herein, FeCoNiCrx (x = 1.5, 1.8, 2.1, 2.4) high-entropy alloy (HEA) coatings were applied to 304 SS using in situ laser cladding (LC) to correlate composition with performance. Microstructure and chemistry were analyzed by XRD, OM, SEM and XPS. Corrosion resistance was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The coatings exhibited dual-phase face-centered cubic (FCC) and body-centered cubic (BCC) structures, with BCC content increasing as Cr increased. The Cr1.8 coating demonstrated the best corrosion resistance in 0.1 M sulfuric acid (H2SO4), with polarization resistance (Rp) of 851.1 kΩ cm2 (5.47 times the substrate) and low corrosion current density (Icorr) of 1.173 μA/cm2. As Cr content rose (x ≥ 2.1), galvanic coupling between FCC and BCC phases accelerated localized corrosion, weakening oxide formation and reducing resistance in Cr2.1 and Cr2.4 coatings. In 0.5 M H2SO4, Cr2.4 showed superior resistance, with maximum Rp of 1762.4 kΩ cm2 (11.33 times the substrate) and minimum Icorr of 0.288 μA/cm2, due to a stable Fe–Cr oxide passive film. This study provides insights for designing HEA coatings with enhanced corrosion resistance.