一种强化汽车铝合金析出相的原子分辨电子显微学和谱学研究  

Atomic⁃resolution electron microscopy and spectroscopy study of precipitate phases in a precipitation⁃strengthened automotive aluminum alloy

作　　者：胡谢君 李婷玉 赖玉香 陈江华 HU Xiejun;LI Tingyu;LAI Yuxiang;CHEN Jianghua(Center for High-Resolution Electron Microscopy,College of Materials Science and Engineering,Hunan University,Changsha Hunan 410082;Pico Electron Microscopy Center,Innovation Institute for Ocean Materials Characterization Technology,Center for Advanced Studies in Precision Instruments,Hainan University,Haikou Hainan 570228;Key Laboratory of Pico Electron Microscopy of Hainan Province,Hainan University,Haikou Hainan 570228,China)

机构地区：[1]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 [2]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 [3]海南大学海南省皮米电子显微学重点实验室,海南海口570228

出　　处：《电子显微学报》2024年第4期454-463,共10页Journal of Chinese Electron Microscopy Society

基　　金：国家自然科学基金资助项目(Nos.U23A20392,52001119,52101007).

摘　　要：原子分辨率的电子显微学和谱学技术是研究析出强化铝合金微结构的最有力的手段和方法,特别是原子分辨率的EDS能谱成像技术为更深入地研究和认识铝合金中的析出强化相颗粒结构及其与铝基体的界面匹配关系至关重要。然而,迄今为止,对于汽车轻量化用Al⁃Mg⁃Si合金中Mg、Si合金元素的亚稳析出聚集颗粒,原子分辨率的EDS能谱成像很难实现。本工作为国内首次报道对汽车用Al⁃Mg⁃Si合金中轻质Mg、Si元素的析出颗粒成功实现原子分辨率的EDS能谱成像的案例。作者利用最先进的透射电子显微镜技术研究了一种典型汽车用Al⁃Mg⁃Si合金在250℃时效强化过程中工艺-微结构-性能的演变关系。研究结果表明,富Mg合金在高温峰值时效阶段析出相的主要类型为β′相(Mg_(9)Si_(5))。通过先进原子分辨率的能谱成像揭示了β′相与Al基体界面层的精细原子结构和元素分布。β′相颗粒最外层总是以Mg原子层对接Al基体,这有助于帮助理解析出相界面能问题。本文的研究结果清楚解答了该合金硬度和屈服强度均得到显著提升的微结构原因。Atomic resolution electron microscopy and spectroscopy techniques are among the most powerful tools for studying the microstructure of precipitation⁃strengthened Al alloys.In particular,atomic resolution EDS(Energy Dispersive Spectroscopy)imaging technology plays a crucial role in deepening our understanding of structures of strengthening precipitates and their interface relationships with the Al matrix.However,achieving atomic resolution EDS imaging of metastable precipitates or clusters of Mg and Si alloying elements in Al⁃Mg⁃Si alloys,which are widely used in automotive applications,has remained challenging until now.This work reports the first successful case of atomic resolution EDS imaging of precipitates containing light elements such as Mg and Si in automotive Al⁃Mg⁃Si alloys in China.We employed state⁃of⁃the⁃art transmission electron microscopy techniques to investigate the process⁃microstructure⁃property evolution in a typical automotive Al⁃Mg⁃Si alloy during aging at 250℃.The result revealed that the primary type of precipitates in Mg⁃rich alloys at high⁃temperature peak aging was theβ′phase(Mg_(9)Si_(5)).Advanced atomic resolution EDS imaging provided detailed insights into the fine atomic structure and elemental distribution of theβ′phase and its interface with the Al matrix.Notably,the outermost layers ofβ′phase particles were consistently terminated with Mg atomic layers,offering valuable insights into the precipitate interface energy.Our findings elucidate the significant improvements in hardness and yield strength of the alloy result ing from its microstructural changes.

关 键 词：Al⁃Mg⁃Si合金 原子分辨能谱成像 析出相 电子显微学 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG115.215.3[金属学及工艺—金属材料]