The study of Li effect on the microstructure and tensile properties of cast Al-Mg2Si metal matrix composite

► 0.15%Li changes the morphology of primary Mg2Si from dendritic to polyhedral shape. ► Optimum Li level for improving both UTS and elongation values is obtained 0.15%. ► Li addition converts the fracture behaviour from brittle to ductile. ► The fracture behaviour is explained in terms of the presence of oxide bifilms.