基于三维原子探针统计学结果的Al-Zn-Mg合金自然时效早期析出动力学研究  

Early-stage precipitation in a naturally aged Al-Zn-Mg alloy based on atom-probe analysis

作　　者：郑嘉玲 秦永贵 刘吉梓[1,2] ZHENG Jia-ling;QIN Yong-gui;LIU Ji-zi(Nano and Heterogeneous Materials Center,School of Materials Science and Engineering,Nanjing University of Science and Technology,Jiangsu Nanjing 210094;Herbert Gleiter Institute of Nanoscience,Nanjing University of Science and Technology,Jiangsu Nanjing 210094,China)

机构地区：[1]南京理工大学异质结构材料中心材料科学与工程学院,江苏南京210094 [2]南京理工大学格莱特纳米科技研究所,江苏南京210094

出　　处：《电子显微学报》2018年第2期128-136,共9页Journal of Chinese Electron Microscopy Society

基　　金：国家自然科学基金资助项目(No.51301064)

摘　　要：借助于显微维氏硬度仪、高角环形暗场扫描透射电子显微镜及三维原子探针对Al-Zn-Mg合金自然时效过程中原子团簇的析出演变规律及其对合金力学性能的影响进行了细致的研究。合金固溶淬火后自然存放一个月,硬度即可增加50 HV达到110 HV,这归因于高数量密度的原子团簇的析出。这种自然时效原子团簇的形貌与文献报道的GPI区的球状形貌具有相似性,但缺乏明显的晶体学结构特征且成分不唯一,Zn/Mg原子比的分布范围也较广。当自然时效时间延长至三个月,合金的硬度将继续保持在110 HV左右,没有明显的提升,这是因为一个月到三个月期间原子团簇的体积分数并没有改变。但相比自然时效一个月的试样,自然时效三个月的试样中原子团簇的衬度越来越明显,Zn/Mg原子比也越来越集中,出现了成分收敛。Clusters formation and its influence on hardness during natural aging for up to 90 days have been investigated using hardness test and high-angle annular dark-field scanning transmission electron microscopy,together with atom-probe tomography analysis.Owing to a great number of clusters precipitated in samples naturally aged for 30 days,the hardness value reaches 110 HV with the increment of 50 HV.These spherical clusters seem like the reported GPI zones in morphology,but have no distinguished crystallographic feature.Besides,the composition of these clusters is different from each other and the measured Zn/Mg atomic ratios are in a wide range.And then,as time goes on,the hardness of alloys remain near 110 HV,due to no more clusters nucleation or clusters coarsening.It is interesting that during this period clusters self-adjust in chemistry and the most prominent change is the convergence of Zn/Mg atomic ratios with aging time and cluster size.

关 键 词：铝合金 原子团簇 自然时效 APT HAADF-STEM 

分 类 号：TG146.2[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]