Thermal deformation behavior and microstructure evolution of AA6061 aluminum alloy with trace rare-earth Y added

A Gleeble-3500 thermal simulator was employed to conduct hot compression tests on AA6061 aluminum alloy containing 0.15 wt% yttrium (Y). The hot deformation behavior and microstructural evolution were systematically investigated under varying temperatures (350–550 ℃) and strain rates (0.01–10 s⁻¹) at a constant strain of 66.7 %. The results indicate that the Y-modified alloy exhibits a high sensitivity to both strain rate and deformation temperature, with increasing strain rate and decreasing temperature synergistically elevating the flow stress. The calculated thermal activation energy (Q) of 228.57 kJ/mol suggests a strong resistance to deformation. Microstructural analysis reveals that the addition of Y promotes grain refinement, effectively suppressing the growth of β-AlFeSi and Mg₂Si phases while hindering dislocation motion and grain boundary migration. Elevated temperatures facilitate dynamic recrystallization, wherein initially elongated grains induced by deformation are progressively transformed into uniformly distributed equiaxed grains through coordinated mechanisms of dislocation rearrangement and subgrain formation.