Mg-controlled formation of Mg-Ag co-clusters in initial aged Al-Cu-Mg-Ag alloys

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• 作者：Song Bai ; Zhiyi Liu ; ^{liuzhiyi@mail.csu.edu.cn" class="auth_mail} ; Xuanwei Zhou ; Peng Xia ; Sumin Zeng
• 关键词：Al&ndash ; Cu&ndash ; Mg&ndash ; Ag alloys ; Age-hardening ; Clusters ; Nucleation ; Atom probe tomography
• 刊名：Journal of Alloys and Compounds
• 出版年：25 July, 2014
• 年：2014
• 卷：602
• 期：Complete
• 页码：193-198
• 全文大小：2222 K

文摘

The effect of Mg variations on the number density, solute concentrations and sizes of Mg-Ag co-clusters at the early aging stage, as well as the age-hardening response of different Al-Cu-Mg-Ag alloys, was well investigated by a combination of Vickers hardness measurement, transmission electron microscopy (TEM) and atom probe tomography (APT). The strongest age-hardening response at 165 掳C was found in 0.81Mg alloy, accompanied by the highest nucleation rate of Mg-Ag co-clusters after aging for 0.5 h. However, the least response was revealed in 0.39Mg alloy. By quantitative APT analysis, the observed trend in the total number density of Mg-Ag co-clusters suggested the following order: 0.81Mg alloy > 0.39Mg alloy > 1.18Mg alloy. This parabolic change in the total number density of Mg-Ag co-clusters with increasing Mg highlighted the existence of a critical Mg content, which contributed to the greatest nucleation kinetics of Mg-Ag co-clusters. As Mg increased from 0.39 to 0.81, the formation of small Mg-Ag co-clusters was significantly promoted, whereas the number density of large Mg-Ag co-clusters almost remained constant. Moreover, the remarkable enrichment of Cu within Mg-Ag co-clusters indicated that the accelerated evolution from Mg-Ag co-clusters to 惟 phase was responsible for the lowest number density of Mg-Ag co-clusters in 1.18Mg alloy after aging at 165 掳C for 0.5 h.