The corrosion behavior of 5A05 aluminum alloy in 3.5 wt.% NaCl solution was investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared (FT-IR) spectroscopy and electrochemical impedance spectroscopy (EIS) test, and the corrosion mechanism was also discussed. The results showed that the corrosion rates of the 5A05 alloy were low and decreased with the increase in immersion time. Under the conditions of exposure studied, this alloy suffered from pitting corrosion that took place from or around the intermetallic particles existing in the alloy. The number and size of the hemispherical corrosion pits on the sample surfaces increased with the increase of the test time. The dark-grey layer of corrosion products formed on 5A05 aluminum alloy in 3.5% NaCl solution contained many microcracks. Furthermore, XPS and FT-IR analysis proved that the corrosion products were mainly composed of Al 2 O 3 , Al(OH) 3 and AlCl 3 .

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The atmospheric corrosion behavior of antirust aluminum alloys 3A21 and 5A05 in industrial and coastal atmospheres was investigated and compared. Weight loss results, together with corrosion morphology characterization, suggest that the coastal atmosphere is much more corrosive to antirust aluminum than the industrial atmosphere. 5A05 alloy has better localized corrosion resistance than 3A21 alloy, and the corrosion rate shows a decreasing tendency with exposure time. After 3 years of exposure, the antirust aluminum samples only suffer pitting corrosion attack and retain their mechanical properties well. In the two atmospheres, the corrosion products are mainly oxides, aluminum hydroxychloride, aluminum sulfate hydrate, and basic aluminum sulfate. Besides, the atmospheric corrosion mechanism and the corrosion comparison between the two atmospheres were also discussed.