Ultra-corrosion-resistant aluminum alloys achieved by femtosecond laser complete remediation of microarc oxidation defects

• Published in: Applied surface science 2024-08, Vol.663, p.160160, Article 160160
• Main Authors: Hu, Longjin, Yan, Dandan, Zou, Tingting, Xu, Jiapei, Li, Lin, Zhang, Ruizhi, Yang, Jianjun
• Format: Article
• Language: English
• Subjects: Aluminum alloys; Amorphous-nanocrystals; Anti-corrosion; Femtosecond laser processing; Microarc oxidation; Superhydrophobic surface
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2024.160160

[Display omitted] •Inherent micropore-cracks on the MAO surface are eliminated by the femtosecond laser;•The alumina nanocrystallines (γ-Al2O3 and α-Al2O3) are formed and embedded into the original amorphous layer;•Material surface becomes the intrinsically superhydrophobic even at high temperatures;•The measured corrosion current falls to an unprecedent value of 1.46 × 10-13 A/cm2. Microarc oxidation (MAO) is a widely employed technology for the corrosion protection of metal surfaces due to the formation of thick-layer ceramic substances. However, its practical effectiveness is strictly limited by the inevitable concomitant generation of numerous microscale pores/cracks on the oxidation surface to directly expose the substrate materials. As concerning this problem, we here introduced a novel method of the femtosecond laser irradiation to completely eliminate the above MAO defects on aluminum alloys, which consequently modulates the passivation layer into the dense and the superhydrophobic. Meanwhile, with the deep insights into the phase composition variations of the oxide layer, we can find that the laser treatments enable the development of both γ-Al2O3 and α-Al2O3 nanocrystallines with embedment in the amorphous substances to significantly improve the chemical stability of materials. Such laser modifications eventually result in the ultra-corrosion-resistant surface of aluminum alloys, with the measured corrosion current density of 1.46 × 10-13 A/cm2 as well as the impedance value over 112 GΩ∙cm2, about two orders of magnitude enhancement in the anticorrosion compared to the initial MAO sample.