Corrosion mechanism of annealed 2050 Al-Li alloy under the influence of multiple factors

• The increase of high-angle grain boundaries accelerated corrosion. • The release of stored energy improves corrosion resistance. • The decrease in second phases enhances corrosion resistance. • Second phases have the greatest impact and stored energy have the least impact. The density of Al-Li alloy is reduced due to the addition of Li, thus enabling it to be widely used in the aerospace field. However, this beneficial property comes with a substantial compromise in corrosion resistance, posing significant challenges for practical implementation. Therefore, during the annealing process, the microstructure changes under different degrees of recrystallization were systematically studied on the corrosion performance of 2050 Al-Li alloy. The influencing factors of misorientation angles, stored energy, and second phases were mainly selected for research. As the degree of recrystallization deepens, the fraction of high-angle grain boundaries (HAGBs) increases, leading to a decrease in resistance to corrosion Meanwhile, stored energy is released and the number density of second phases decrease, thereby enhancing corrosion resistance. The quantitative analysis extracted from microstructural parameters further revealed the corrosion mechanism and the proportion of influence of different factors, and based on this, a corrosion model was established. According to the corrosion model, second phases have the greatest impact, followed by grain boundaries, and stored energy have the least impact.