Modeling-Based Processing of Al-Li Alloys for Delamination Resistance

Al-Li alloys are of interest for use in aerospace structures due to the desirable combination of high strength and low density. However, high strength Al-Li alloys exhibit an intergranular delamination fracture mode which has limited widespread structural applications. Previous work at NASA LaRC, under limited testing, found that the failures tend to be between grains of the two Brass texture component variants. Taylor Factor calculations show these to have severe strain incompatibility. These grain orientations are known to develop as a preferred orientation in Al-Li-X-Zr alloys during severe, hot rolling. This program will verify the results and work with Industry to develop an alternative, delamination-free process.