石奥杰, 李佳声, 王莉, 任玉平, 刘冬艳, 马骁, 董加胜, 楼琅洪. 高强韧性AZ91镁合金异构组织形成机制及强韧化机理[J]. 金属学报, DOI: 10.11900/0412.1961.2025.00276.

摘要 相关文章 Metrics 全文: PDF(3157 KB)   摘要: 传统AZ91镁合金存在强度与塑性难以同时提高的矛盾。为解决此问题，本工作在AZ91镁合金中构建了两种不同的异构组织：由变形粗晶和动态再结晶细晶交替分布的层状晶粒异构组织、完全由再结晶晶粒组成的双峰晶粒异构组织。力学性能测试结果表明，层状晶粒异构组织的AZ91镁合金具有更好的强塑性匹配。利用SEM滑移迹线表征技术和数字-图像相关(DIC)技术等测试手段，对两种异质结构AZ91镁合金的塑性变形行为进行了研究。结果表明：两种异构组织合金的细晶中均激活了基面滑移和非基面滑移，部分晶粒间发生滑移传递，有效减缓了晶间应力集中。粗晶区具有较高的位错存储能力，变形后期粗晶内产生孪晶，协调其在c轴方向的变形，抑制裂纹扩展，使得两种异构组织AZ91镁合金均表现出较高的加工硬化能力和均匀延伸率。双峰晶粒异构组织AZ91镁合金的室温屈服强度(YS)约234.5 MPa，抗拉强度(UTS)约337.5 MPa，延伸率(EL)约23.8%，层状晶粒异构组织合金得益于变形粗晶区位错密度更高、细晶区晶粒尺寸更小，在保持高塑性(EL ≈ 21.3%)的同时，其强度显著提升(YS ≈ 274.9 MPa，UTS ≈ 377.1 MPa)，展现出更为优异的强塑性结合。 关键词 ： 镁合金,  异质结构,  高强韧性,  变形机制     Abstract：Magnesium alloys have attracted significant attention owing to their low density and high specific strength, offering broad application prospects in lightweight aerospace and automotive components. However, the limited number of activatable slip systems inherent to their hexagonal close-packed structure severely restricts ductility and work-hardening capacity, posing a persistent challenge in achieving a synergy between strength and ductility. Heterogeneous structure design is considered an effective strategy for attaining such a balance in metallic materials. In this work, AZ91 magnesium alloys with a lamellar grain structure (LGS) and a bimodal grain structure (BGS) were fabricated via thermomechanical processing combined with controlled annealing, achieving a synergistic enhancement of strength and ductility. The LGS was produced by rapid extrusion, resulting in a lamellar microstructure characterized by alternating dynamically recrystallized (DRX) fine grains (average ~3.6 µm) and deformed coarse grains (average ~24.0 µm). The BGS was obtained by annealing the extruded alloy, leading to fully statically recrystallized coarse grains (average ~13.0 µm) coexisting with DRX fine grains (average ~5.2 µm). Mechanical testing showed that both heterogeneous structures exhibited pronounced work-hardening capability and improved uniform elongation. The BGS alloy demonstrated a yield strength (YS) of ~234.5 MPa, an ultimate tensile strength (UTS) of ~337.5 MPa, and elongation (EL) of ~23.8%. In contrast, the LGS alloy exhibited significantly higher strength (YS ≈ 274.9 MPa; UTS ≈ 377.1 MPa) while maintaining excellent ductility (EL ≈ 21.3%). This improvement is attributed to the combined effects of higher dislocation density in the deformed coarse-grained regions and the finer grain size in the fine-grained domains. In this study, multi-scale characterization techniques, including SEM-based slip trace analysis and digital image correlation, were employed to elucidate the deformation mechanisms. The results indicate that, at the early stage of deformation (~8% strain), both basal and non-basal slip systems were activated in the fine-grained regions of the two heterostructured alloys. In addition, basal-to-basal and basal-to-non-basal slip transfer occurred between adjacent grains, effectively alleviating intergranular stress concentration. Meanwhile, the coarse-grained regions exhibited a high dislocation storage capacity, and deformation twinning was activated at later deformation stages to accommodate c-axis strain. As a result, both heterostructured alloys (LGS and BGS) demonstrated strong work-hardening behavior, with the LGS alloy achieving a superior combination of strength and ductility. The findings contribute to a deeper understanding of the plastic deformation mechanisms in heterostructured magnesium alloys and provide a feasible pathway for enhancing their mechanical performance. Key words： Magnesium alloys    Heterostructure    High strength-toughness    Deformation mechanism 收稿日期: 2025-09-18      基金资助:中国科学院先导专项项目(No.XDC0160201) 服务 把本文推荐给朋友 加入引用管理器 E-mail Alert RSS 作者相关文章 石奥杰 李佳声 王莉 任玉平 刘冬艳 马骁 董加胜 楼琅洪 44.8K 链接本文: https://www.ams.org.cn/CN/Y0/V/I/0 [1] 崔天亮, 谢兴飞, 温晓灿, 吕少敏, 曲敬龙, 杜金辉. GH4151难变形高温合金的拉伸行为及其断裂失效机制[J]. 金属学报, 2026, 62(3): 445-457. [2] 阴嘉琳, 石磊, 武传松. 超声振动对镁/铝异质合金搅拌摩擦搭接焊接头界面组织演变的影响[J]. 金属学报, 2026, 62(1): 133-147. [3] 吴泽威, 颜俊雄, 胡励, 韩修柱. 双峰分离非基面织构AZ31镁合金板材反常中温轧制变形行为及机理[J]. 金属学报, 2025, 61(8): 1165-1173. [4] 游云翔, 谭力, 高静静, 周涛, 周志明. 利用热轧制-剪切-弯曲工艺及退火调控Mg-Al-Zn-Mn-Ca 镁合金的织构[J]. 金属学报, 2025, 61(6): 866-874. [5] 曾小勤, 于铭迪, 王静雅. 镁合金的多系滑移与塑性调控[J]. 金属学报, 2025, 61(3): 361-371. [6] 王慧远, 孟昭元, 贾海龙, 徐新宇, 花珍铭. 新型低合金含量烘烤硬化镁合金研究进展及展望[J]. 金属学报, 2025, 61(3): 372-382. [7] 蒋斌, 张昂, 宋江凤, 黎田, 游国强, 郑江, 潘复生. 镁合金一体化压铸缺陷控制[J]. 金属学报, 2025, 61(3): 383-396. [8] 黄科, 李新志, 方学伟, 卢秉恒. 镁合金电弧熔丝增材制造技术研究现状与展望[J]. 金属学报, 2025, 61(3): 397-419. 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