Abstract: The electrochemical features of commercial airframe material, Al alloy LY12, in 0.349mol/L neutral sodium chloride (NaCl) and sodium sulfate (Na2SO4) solutions were investigated by electrochemical impedance spectroscopy (EIS) and potentiody-namic polarization techniques. The microstructure of the as-tested samples was stud-ied by scanning electron microscopy. The results show that the Nyquist plots of LY12 at different immersion time displayed different features, indicating that the Cl^- ions elevate the corrosion rate and inhibit the repassivation of a metastable pit. It also shows that the corrosion product of LY12 formed in SO4^2- solution isn't easy to dis-solve, and it urill cover the surface of working electrode in the electrolyte. SEM images indicate that the corrosion apparent area and pit number of LY12 in NaCl solution are greater than that in Na2SO4 solution.

Key words: LY12 aluminum alloy, pitting corrosion, electrochemical impedance spectroscopy,