Unlocking high thermal stability in dilute Al alloys: Introducing nanograins with minimal surface configuration

Ultralow temperature rolling with large strain deformation has been demonstrated as an effective method to produce high strength sheets. In this study, high strength 6061 aluminum alloy sheets were successfully fabricated using an ultralow temperature rolling process, and their thermal stability was thoroughly investigated. Experimental results indicate that, accompanied by grain boundary relaxation, nanocrystalline grains with minimized surface configurations formed within the aluminum alloy material. The introduction of these nanocrystalline grains significantly enhanced the material thermal stability. The ultralow temperature rolled 6061 aluminum alloy exhibited a tensile strength (σ_r) of 453 MPa at room temperature, 0.8σ_r at 200 °C, and 0.68σ_r at 300 °C. The ultralow temperature rolled 6061 aluminum alloy sheets maintained a tensile strength above 300 MPa in environments below 300 °C, meeting the demand for high strength aluminum alloy materials in moderate temperature environments.