Segregation of alkaline earth metals at grain boundaries is investigated as a cause of grain boundary embrittlement in Aluminum alloys. Auger spectroscopy shows that grain boundary segregation of Na occurs in an AlLi alloys. In addition, Aluminum extracted from bauxite bring in alkali impurities. First-principles simulation allows us to understand the energetics of Na segregation at grain boundaries and model the decreased grain boundary cohesive energy. Using this data within the concomitant dislocation theory based on our recent work, we study the effect of Na segregation on static and fatigue fracture of Al-Li alloys. Using DFT calculations, we describe how the presence of alkali impurities could possibly enhance hydrogen embrittlement
