Herein, aging prior to extrusion is used to regulate the microstructure and mechanical properties of an extruded AZ91 alloys. The results show that pre‐aging can induce numerous precipitates in Mg matrix to refine the recrystallized microstructure during hot extrusion of AZ91 alloys. After extrusion, most precipitates distribute at grain boundaries, suppressing grain growth. Thus, coupling pre‐aging and hot extrusion can effectively enhance the yield strength of the AZ91 alloy and maintain considerable plasticity (>15%) simultaneously. In contrast, the improvement in mechanical properties is not so effective by direct extrusion and subsequent heat treatment. Although the subsequent aging (T6 treatment) can induce dense precipitates inside grains generating strong precipitation hardening, it badly reduce the tensile ductility (to 6.3%) as well. Moreover, the T6 treated sample also exhibits lower yield strength compared with the extruded sample via coupling pre‐aging and hot extrusion. Based on the experimental analyses, the underline mechanisms are discussed.

中文翻译：

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挤压前时效对挤压AZ91合金组织和力学性能的影响

在此，挤压之前的时效用于调节挤压的AZ91合金的组织和力学性能。结果表明，预时效可在AZ91合金热挤压过程中在Mg基质中诱导大量析出物，以细化重结晶的微观结构。挤出后，大多数沉淀物分布在晶界，从而抑制了晶粒的生长。因此，将预时效和热挤压相结合可以有效地提高AZ91合金的屈服强度，并同时保持可观的可塑性（> 15％）。相反，通过直接挤出和随后的热处理，机械性能的改善不是那么有效。尽管随后的时效处理（T6处理）会在晶粒内部诱发致密的沉淀物，从而产生强的沉淀硬化，但也会严重降低拉伸延展性（至6.3％）。此外，经T6处理的样品与通过预时效和热挤压相结合的挤出样品相比，还具有较低的屈服强度。在实验分析的基础上，讨论了下划线机制。