预变形对Al-4.0Cu-0.9Li-0.2Mg合金微观结构和力学性能的影响

预变形对Al-4.0Cu-0.9Li-0.2Mg合金微观结构和力学性能的影响

魏少青，李石勇 *，伍翠兰，陈江华*

（1. 海南大学精密仪器高等研究中心，海洋材料表征技术创新研究院，皮米电镜中心，海南 海口570228；2. 海南大学海南省皮米电子显微学重点实验室，海南 海口 570228；3. 湖南大学材料科学与工程学院高分辨电镜中心，湖南 长沙 410082）

摘 要 通过显微硬度测试、拉伸力学性能测试、透射电子显微镜观察等手段，研究了预变形工艺对时效Al-4.0Cu-0.9Li-0.2Mg (wt.%)合金微观结构和力学性能的影响。结果表明，时效前引入预变形的T8工艺能显著加快合金的时效响应速率并提高合金的峰值时效强度，但合金的延伸率却明显降低。未变形合金在160 ℃下峰值时效时主要析出相为δ'/θ'/δ'共生相和T1相，引入预变形的合金中主要析出相均为T1相，而δ'/θ'/δ'共生相的析出则明显受到抑制，并且随着变形量的增加，合金中δ'/θ'/δ'共生相的数量也越来越少，而T1相也逐渐变得更加细小。T8工艺促进了形变强化和析出强化，使得合金强度提高，但预变形的引入使得合金在后续变形过程中更容易产生位错塞积，因此合金塑性明显下降。引入变形后合金中存在着大量的位错，给T1相的形核析出提供了大量的异质形核点，又由于合金中的溶质原子数量有限，因此δ'/θ'/δ'共生相的析出受到抑制。

关键词 Al-Cu-Li-Mg合金；形变时效；微观结构；力学性能；透射电子显微镜

中图分类号： TG146.2+1；TG115.21+5.3；TG113 文献标识码：A Doi:10.3969/j.issn.1000-6281.2025.02.003

Effects of pre-deformation on the microstructure and mechanical properties of Al-4.0Cu-0.9Li-0.2Mg alloy

WEI Shaoqing，LI Shiyong*，WU Cuilan，CHEN Jianghua*

(1. Pico Electron Microscopy Center, Innovation Institute for Ocean Materials Characterization, Center for Advanced Studies in Precision Instruments, Hainan University, Haikou Hainan 570228; 2. Key Laboratory of Pico Electron Microscopy of Hainan Province, Hainan University, Haikou Hainan 570228; 3. Center for High Resolution Electron Microscopy, College of Materials Science and Engineering, Hunan University, Changsha Hunan 410082，China)

Abstract The effect of the pre-deformation process on the microstructure and mechanical properties of the Al-4.0Cu-0.9Li-0.2Mg (wt. %) alloy was studied using microhardness testing, tensile mechanical property testing, and transmission electron microscope. The results indicate that the T8 process, which involves pre-deformation followed by artificial aging at 160 ℃, significantly accelerates the alloy’s aging response and increases its peak strength. However, this process also leads to a significant reduction in elongation. During peak aging at 160 ℃, the main precipitates in the undeformed alloy are δ'/θ'/δ' composite precipitates and T1 precipitates. In contrast, the T8-treated alloy also predominatly features T1 precipitates, with the precipitation ofδ'/θ'/δ' composite precipitates being significantly suppressed. Furthermore, as the deformation increases, the number of δ'/θ'/δ' composite precipitatesdecreases, while the T1 precipitates becomes gradually finer. The introduction of pre-deformation enhances both deformation strengthening and subsequent precipitation strengthening, leading to an improvement in the alloy’s strength. However, pre-deformation also promotes dislocation pile-up during subsequent deformation, significantly reducing the alloy’s plasticity. The pre-deformd alloy contains a high density of dislocations, which serve as heterogeneous nucleation sites for T1 precipitates. Due to the limited availablity of solute atoms, the preferential formation of T1 precipitates inhibites the precipitation of δ'/θ'/δ' composite precipitates.

Keywords Al-Cu-Li-Mg alloys; pre-deformation and aging; microstructure; mechanical properties; transmission electron microscopy

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