Ultrafine-grained Al-La-Mg-Mn alloy fabricated by melt spinning and hot extrusion with ultrahigh strength and thermal stability.

To enhance the mechanical properties of Al–(La, Ce) alloys, melt spinning and hot extrusion were employed to fabricate Al-La-Mg-Mn alloy with an ultrafine-grained structure (∼0.56 μm). The as-extruded alloy exhibits the highest tensile strength of 621 ± 4 MPa among Al–(La, Ce) alloys fabricated by various methods while retaining an appreciable elongation of 6.8 ± 1.1 %. The high strength is mainly ascribed to the ultrafine grains and high-volume intermetallics, conferring robust grain boundary strengthening and Orowan strengthening effects. Additionally, this study delved into the high-temperature (400°C) coarsening behavior of the intermetallic and grain size. The findings unveil an exceptionally low coarsening rate of the intermetallic at 400°C (3.19×10−33 m4 s−1), accompanied by only slight grain coarsening, underscoring the remarkable thermal stability of the ultrafine-grained structure. • An ultrafine-grained Al-La-Mg-Mn alloy was fabricated by melt spinning and hot extrusion. • The alloy exhibits the highest strength among all Al-(La, Ce) alloys reported to date. • The microstructural evolution at different stages of hot extrusion was systematically studied. • The as-fabricated ultrafine-grained structure exhibits excellent thermal stability up to 400 °C. [ABSTRACT FROM AUTHOR]