Revealing the deformation mechanisms and their effects on mechanical properties of Mg-3Al-1Zn alloy during repetitive continuous extrusion: Experiment and simulation

Le résumé fourni par la source

Severe plastic deformation (SPD) is known to effectively refine microstructure and improve mechanical properties of magnesium alloys. The repetitive continuous extrusion (Re- Conform ) process, compared with conventional SPD routes, enables large accumulated shear strain to be introduced in a continuous and industrially scalable manner, without requiring processing. This work, a unique Re- Conform process is employed to prepare Mg-3Al-1Zn alloy, and in-depth deformation mechanisms under such complicated thermomechanical conditions are investigated by combining experiments, finite-element modelling (FEM) and Visco-plastic self-consistent (VPSC) modeling. The results reveal that Re-Conform process refined the grain size of Mg-3Al-1Zn alloy and achieved a synergistic enhancement of tensile strength and ductility with improved work-hardening capacity through texture regulation. With increasing extrusion passes, the alloy texture transformed from a strong basal {0001}//ED orientation to a tilted fiber texture (≈35° ∼ 70° from ED) with a more homogeneous orientation distribution. Continuous dynamic recrystallization gradually became the dominant mechanism for grain nucleation and orientation reconstruction. The simulations using FEM and VPSC indicated that the inherent shear–thermal coupling significantly promoted basal slip activation and gradually triggered the participation of non-basal < c + a > slip and tensile twinning. Then, a stable multi-slip coordinated deformation mode was formed and thus enhanced strain uniformity and work-hardening capability.

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