In this work, the microstructural evolution of Al–5Mg (wt.%) alloy fabricated by accumulative continuous extrusion forming (ACEF) at room temperature (RT) and cryogenic temperature (CT) was investigated. The grain refinement mechanism during ACEF was revealed. The strengthen and ductility enhancements of the alloy were discussed. The results showed that good grain refinement effect was achieved in the alloy after multi-pass RT-ACEF, and was further enhanced in the alloy fabricated by 1 pass CT-ACEF. High-density dislocations, as the driven force of continuous dynamic recrystallization, were achieved in the 1 pass CT-ACEFed alloy, and the growth of the recrystallized grains was limited at CT. As a result, superior grain refinement effect was obtained in the alloy after CT-ACEF. Simultaneous strength and ductility improvements were found in the ACEFed alloy. The ultimate tensile strength and elongation were enhanced to 294.3 MPa and 55.1% of the alloy after 1 pass CT-ACEF. Grain boundary strengthening and dislocation strengthening dominated the strength enhancement of the ACEFed alloy. The high work hardening exponent and wide strain interval were responsible for the increase in the ductility of the CT-ACEFed alloy. The purpose of this study is to provide a high-efficiency strategy to achieve Al–Mg alloys with superior mechanical performance and overcome the strength-ductility trade-off.

在这项工作中，研究了在室温 (RT) 和低温 (CT) 下通过累积连续挤压成型 (ACEF) 制造的 Al-5Mg (wt.%) 合金的微观结构演变。揭示了 ACEF 期间的晶粒细化机制。讨论了合金的强度和延展性增强。结果表明，经过多道次RT-ACEF后的合金获得了良好的晶粒细化效果，并在1道次CT-ACEF后的合金中进一步增强。高密度位错作为连续动态再结晶的驱动力，在 1 道次 CT-ACEFed 合金中实现，再结晶晶粒的生长在 CT 处受到限制。结果，CT-ACEF后的合金获得了优异的晶粒细化效果。在 ACEFed 合金中发现了强度和延展性的同时改进。极限抗拉强度和伸长率提高到294.3 MPa 和 55.1% 的合金经过 1 次 CT-ACEF。晶界强化和位错强化主导了ACEFed合金的强度提高。高加工硬化指数和宽应变区间是 CT-ACEFed 合金延展性增加的原因。本研究的目的是提供一种高效的策略来获得具有优异机械性能的铝镁合金，并克服强度-延展性的权衡。