Achieving enhanced strength in ultrafine lamellar structured Al2024 alloy via mechanical milling and spark plasma sintering

Recently, mechanical properties improvement through microstructure design has attracted worldwide attention. In the present study, a “bottom to up” route including mechanical milling and spark plasma sintering was employed for fabricating ultrafine lamellar structured Al2024 alloy. Microstructure observation revealed that flake shaped powder with a mean grain size of about 60 nm was obtained by mechanical milling for 20 h. The flake shaped powder self-assembled during sintering, forming a bulk sample with periodic lamellar structure and ultrafine grain size (1.14 µm). Tensile test revealed that the ultrafine lamellar structured alloy exhibited significantly enhanced strength (yield strength 375 MPa, tensile strength 456 MPa) compared to the conventional O-state counterpart, but the tensile ductility was reduced (tensile elongation 5%). Strategies for further optimizing the mechanical properties of the bulk samples were discussed.