Corrosion Behavior of 5A05 Aluminum Alloy in NaCl Solution

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 Al2O3, Al(OH)3 and AlCl3.