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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

胡谢君，李婷玉，赖玉香*，陈江华*
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2024年 第43卷 第4期: 1000-6281（2024）04-454-010     下载地址：

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

胡谢君，李婷玉，赖玉香*，陈江华*

（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）

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，迄今以前，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ꞵ'相（Mg9Si5）。通过先进原子分辨率的能谱成像揭示了ꞵ'相与Al基体界面层的精细原子结构和元素分布。ꞵ'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。

关键词  Al-Mg-Si合金；原子分辨能谱成像；析出相；电子显微学

中图分类号：TG146.21；TG115.21+5.3  文献标识码：A             doi：10.3969/j.issn.1000-6281.2024.05.007

   

Molecular dynamics simulation of the effect of temperature on the tensile plastic deformation of Au nanowires

LIAN Huibin1, WANG Zhanxin1, ZHAI Yadi1*, WANG Lihua1*, HAN Xiaodong1，2*

(1. Beijing Key Laboratory of Advanced Materials Microstructure and Properties, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124；2. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen Guangdong 518000, China)

Abstract   Small-sized gold (Au) nanowires have garnered significant attention due to their excellent mechanical properties. However, most previous studies have focused on room temperature, with limited research exploring their behavior at low temperatures. Investigating the plastic deformation behavior of gold nanowires at low temperatures can provide a theoretical foundation for their applications in such environments. In this paper, molecular dynamics simulations were employed to examine the mechanical behavior of rhombic Au nanowires across different temperatures. The study revealed that the strength and plastic deformation capability of Au nanowires increased as the temperature decreased. Moreover, the plastic deformation mechanism of Au nanowires underwent a temperature-dependent transition. In the temperature rangeof 175 K to 350 K, the plastic deformation mechanism was primarily governed by the emission of Shockley partial dislocation, which led to the generation of numerous stacking fault within the nanowires, followed by shear and premature necking. At lower temperatures, ranging from 50 K to 140 K, the mechanism shifted to partial dislocation emission, initially forming smooth twin boundaries and undergoing migration. This was followed by the formation of intersecting twin boundaries, which continued to migration. This process generated a substantial amount of twinning and resulted in superplastic deformation of up to 40.16 %.

Keywords  molecular dynamics simulation; Au nanowires; plastic deformation; twins; Face-centered cubic metal

 

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