Influence of rolling deformation and solution treatment temperature on the microstructure and mechanical properties of rapidly solidified Al-Mg-Si alloys

Abstract Rapidly solidified Al-Mg-Si alloys are highly desirable in the aerospace and automotive industries because of their excellent potential in terms of light weight and high performance, but the unclear synergistic effects of cold rolling deformation and solution treatment temperature on their microstructure and mechanical properties limit the optimization of the strength-ductility balance for industrial applications. On this basis, the effects of rolling deformation and solution treatment temperature on the microstructural changes and associated mechanical properties of Al-Mg-Si alloys were investigated. The rapidly solidified Al-Mg-Si alloy was subjected to cold rolling with deformation degrees of 50%, 65%, and 80%, followed by solution treatment at 530, 550, and 570 °C for 5 min and artificial aging at 75 °C. The microstructural characteristics were analyzed via EBSD, SEM, and XRD, whereas the mechanical properties were evaluated through tensile tests and Vickers hardness measurements. The results indicate that, after T6 heat treatment, alloys with greater rolling deformation exhibit less Si enrichment at the grain boundaries and finer grains. However, an increased solution temperature has both positive and negative impacts on the material strength. At 550 °C, complete recrystallization and uniform dispersion of the Mg 2 Si and Mg 5 Si 6 phases are promoted, whereas at 570 °C, abnormal grain growth in the medium-deformation samples is induced. Ultimately, the optimal rolling deformation and solution temperature for the good strength-ductility trade-off of the alloy were ascertained. The alloy achieves the optimal strength-ductility balance at 80% rolling deformation and a 550 °C solution temperature, exhibiting a yield strength of 117.0 MPa, a tensile strength of 230.3 MPa, and an elongation of 32.7%.