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Si元素对高Cu/Mg比Al-Cu-Mg合金析出行为的影响

发表时间:2017-12-29  浏览量:1189  下载量:151
全部作者: 刘路,牛凤姣,陈江华,周斌,伍翠兰
作者单位: 湖南大学材料科学与工程学院高分辨电镜中心
摘 要: 利用高角度环形暗场扫描透射电子显微镜(high-angle annular dark-field scanning transmission electron microscopy,HAADF-STEM)系统研究Al-5.0Cu-0.3Mg 合金和Al-5.0Cu-0.3Mg-0.3Si 合金的析出序列。通过对比阐述Si 元素的添加对合金析出的影响,详细揭示了含Si 合金在180℃等温时效时θ'(Al2Cu)相的形核生长过程,发现作为θ'相异质形核点的Q''相的形成是时效早期较快的时效动力学及较高硬度的主要原因。由于Q''相的尺寸很细小,θ'相的粗化被显著限制。因此,绝大部分θ'相的厚度仅为2cθ',并且在所观察的整个时效阶段不会发生明显粗化。与Al-Cu-Mg 合金中不同的θ'相的生长机制最终导致了细小的θ'相形貌,包括θ'相的厚度和径厚比两方面。θ'相的厚度分布对Al-Cu-Mg-(Si)合金时效后期的机械性能影响不大。
关 键 词: 金属材料;Al-Cu-Mg 合金;时效硬化;析出行为;透射电子显微镜
Title: Effect of Si on precipitation in Al-Cu-Mg alloy with high Cu/Mg ratio
Author: LIU Lu, NIU Fengjiao, CHEN Jianghua, ZHOU Bin, WU Cuilan
Organization: Center for High-Resolution Electron Microscopy, College of Materials Science & Engineering, Hunan University
Abstract: The precipitation sequences in Al-5.0Cu-0.3Mg alloy and Al-5.0Cu-0.3Mg-0.3Si alloy have been systematically investigated by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The results are compared to clarify the effect of Si addition. The nucleation and growth process of θ' (Al2Cu) phase in Si-containing alloy during isothermal ageing at 180℃ is revealed in detail. The formation of Q''-type precipitates, on which the θ' precursors nucleate heterogeneously, contributes to the considerable increase in the ageing kinetics and higher strength at the early ageing stage. The thickening of the θ' precipitate is largely confined due to the rather small size of fine Q''-type precipitate. As a result, a large proportion of θ' phase precipitates possess a specific thickness of 2cθ' and change slightly during the entire observed duration of ageing. The θ' growth mechanism distinct from the Al-Cu-Mg alloy finally leads to a refined θ' morphology regarding the thickness and aspect ratio. The θ' precipitate thickness distribution is demonstrated to have little effect on the mechanical property steadiness at the late aging stage of the Al-Cu-Mg-(Si) alloys.
Key words: metallic materials; Al-Cu-Mg alloys; age hardening; precipitation behavior; transmission electron microscopy
发表期数: 2017年12月第24期
引用格式: 刘路,牛凤姣,陈江华,等. Si元素对高Cu/Mg比Al-Cu-Mg合金析出行为的影响[J]. 中国科技论文在线精品论文,2017,10(24):2734-2745.
 
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