Corrosion behavior of Pb-39Mg-10Al-1.5B alloy in sodium halide solutions

The electrochemical corrosion behavior of Pb-39Mg-10Al-1.5B alloy in 3.5 wt% NaX (X = F, Cl, Br and I) sodium halide solutions was investigated by polarizing curve test, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), aiming to assess the corrosion damage degree of the alloy in the cooling waters containing halide elements. The results of polarizing curves, EIS and EN indicate that the corrosion resistance of Pb-39Mg-10Al-1.5B alloy in these sodium halide solutions is in the order of NaF > NaI > NaBr > NaCl. The obtained pitting characteristic frequency fn and noise resistance Rn reveal that the corrosion type of the alloy in NaF and NaI solutions is localized corrosion and that in NaCl and NaBr solutions mainly is general corrosion. Magnesium is the most prone to corroded phase in Pb-39Mg-10Al-1.5B alloy. The corrosion of magnesium is influenced by the corrosion product layer that the compact corrosion product layer can prevent its corrosion while the porous one can accelerate its corrosion. [Display omitted] •The corrosion resistance of the alloy is in the order of NaF > NaI > NaBr > NaCl.•Magnesium is the most susceptible to corrode in Pb-39Mg-10Al-1.5B alloy.•Cl− and Br− ions in the cooling water are more corrosive to the alloy.