Novel combination of indicators to compare the corrosion behaviors of Al, Al-Li alloy 2A97, and other Al alloys

Al-Li alloys have higher mechanical properties and are more lightweight than pure aluminum and other aluminum alloys. The element lithium is highly active; therefore, it is necessary to evaluate corrosion behaviors of Al-Li alloys. However, the existed methods and indicators that compare their corrosion properties are hard to characterize the continuous variations of corrosion performances with time. The potentiostatic polarization measurement is first proposed to compare corrosion resistances of Al, Al-Li alloy 2A97, and Al alloys 2024, 6061, 7050 in this study. Polarization current densities of these materials are measured. Then, equivalent resistances and charges amounts are respectively derived by Ohm's law and integration. Mass losses of these materials are calculated with Faraday's law. Measured current densities and three derived indicators above are applied to compare corrosion behaviors of these materials. Comparative results indicate that alloy 2A97 possesses the best corrosion property at the initial corrosion stage. During steady corrosion processes, the corrosion resistance of alloy 2A97 is better than those of alloys 2024, 6061, and Al except alloy 7050.