Abstract:Mg-39Pb-11.5Al-1B-0.4Sc alloy was prepared by melting method, and the corrosion behaviors and mechanisms in 3.5 wt.% NaX (X = F, Cl, Br, and I) solutions were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), polarization curve test, and electrochemical impedance spectroscopy (EIS). The results show that the phases of Mg-39Pb-11.5Al-1B alloy are α-Mg, Mg₂Pb, Mg₁₇Al₁₂ and AlB₂. The addition of Sc can refine the microstructure significantly. The corrosion resistance of Mg-39Pb-11.5Al-1B-0.4Sc alloy in NaX solutions is in the order of NaCl < NaBr < NaI < NaF. During the corrosion process in NaX (X=Cl, Br, and I) solutions, Mg is first dissolved, then Mg₂Pb is dissolved, and finally Mg₁₇Al₁₂ is fallen off from matrix. The corrosion products of Mg and Mg₂Pb are Mg(OH)₂ and MgO, respectively.

Key words: Mg-39Pb-11.5Al-1B-0.4Sc alloy; halogen solutions; polarization curve; electrochemical impedance spectroscopy (EIS); microstructure; corrosion performance