The corrosion of a novel Mg-11Li-3Al-0.5RE alloy in alkaline NaCl solution

The effects of Cl− concentration and pH value on corrosion behavior of Mg-11Li-3Al-0.5RE alloy in alkaline NaCl solutions were studied through analyzing the corrosion rate, potentiodynamic polarization and impedance spectroscopy. The structure and morphology of the corroded surface was researched by XRD and SEM. The results showed that the increase in concentration of NaCl led to a decrease in Rsol, Rt, and Rf. This means that corrosion developed more seriously with the increase in Cl− concentration. The Ecorr shifted towards positive direction as the pH value increased, at the same time Icorr decreased. In the NaCl solution of pH 12, there existed obviously passivating stage in the corrosion process, which indicated that the corrosion rate was slowed down. The main corrosion mechanism was the selective pitting characteristics of Cl−. And the corrosion products on alloys surface consisted of Mg(OH)2, Al2O3, Li2O2.