Effects of magnesium chloride-based multicomponent salts on atmospheric corrosion of aluminum alloy 2024

Atmospheric corrosion of aluminum alloy 2024 (AA2024) with salt lake water was simulated through a laboratory- accelerated test of cyclic wet-dry and electrochemical techniques. Effects of the soluble magnesium salt contained in the salt water were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), electron probe micro analyzer (EPMA), X-ray diffraction (XRD), infrared transmission spectroscope (IR), and atmospheric corrosion monitor (ACM). The results showed that, with the deposition, atmospheric corrosion of AA2024 could occur when the relative humidity (RH) was lower than 30%. A main crystalline component of corrosion products, layered double hydroxides (LDH), [Mg1-xAlx(OH)2]x+Clx−·mH2O (LDH-Cl), was determined, which meant that magnesium ion played an important role in the corrosion process. It not only facilitated the corrosion as a result of deliquescence, but also was involved in the corrosion process as a reactant.