Abstract

Magnesium-lithium alloy is the lightest alloy among non-toxic materials so far. It is used in aerospace, military, 3C electronics and automotive manufacturing. Poor corrosion performance is the main problem in the application of magnesium-lithium alloy. Therefore, this paper studies the corrosion resistance of Mg-Li-Al-Y-Mn alloy to seek ways to improve the corrosive performance of magnesium-lithium alloy. Multi-directional forging and asymmetric rolling are a new type of severe plastic deformation combined approach, which can effectively refine the grain. Therefore, multi-directional forging and asymmetric rolling are used to prepare Mg-9.55Li-2.92Al-0.027Y-0.026Mn alloy plate and study the alloy corrosion resistance by dynamic potential polarization curve and corrosion reaction thermodynamics. Compared to the dynamic potential polarization curve, it is found that the corrosion potential shifted from -1.5936v to -1.3687v, and the corrosion current density decreased from 1.1604×10^-1mA.cm^-2 to 1.7689×10-4mA.cm^-2, and the average corrosion rate decreased from 2.6515mm.a-1 to 4.0419×10^-3mm.a^-1, a difference of three orders of magnitude, so the corrosion resistance of the alloy is greatly improved. Thermodynamic evaluation of corrosion reaction shows that the reaction film formed by Mg(OH)₂(s), LiOH(s), Li₂CO₃(s), and MgCO₃(s) is beneficial to prevent further surface corrosion. This study shows that the corrosion resistance of the alloy is improved by multi-directional forging and asymmetric rolling, and thermodynamic evaluation provides basic data for the corrosion mechanism of the alloy.

Keywords: Mg-Li-Al alloy; Forging; Asymmetric rolling; Corrosion; Thermodynamics