| Abstract Scope |
Al–7Si–0.8Mg–xLi (x = 0, 0.5, 1 wt.%) alloys were processed via squeeze casting, peak aging, and subsequent high-pressure torsion (HPT) to investigate the combined effects of Li addition, severe plastic deformation, and annealing on microstructure and mechanical properties. Li addition refined the as-aged grain structure, while HPT induced significant grain refinement, reaching a steady-state ultrafine structure after 3 turns. Post-deformation annealing at 250–350 °C resulted in homogeneous grain growth, whereas 450 °C led to heterogeneous microstructures due to abnormal grain growth. The HPT-processed alloys exhibited maximum strength but limited ductility, while annealing improved ductility at the expense of strength. Notably, samples annealed at 450 °C showed enhanced strength compared to 350 °C due to heterostructure strengthening. Fractographic and EBSD analyses revealed that Li-containing alloys exhibited premature failure associated with cracking of coarse Al–Si–Li phases, limiting strain accommodation. |