Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents
Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents
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DOI：
10.1016/j.msea.2016.05.060
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发表时间：
2016-07
期刊：
影响因子：
6.4
通讯作者：
M. Guo;Y. Zhang;X. K. Zhang;J. Zhang;L. Zhuang
中科院分区：
文献类型：
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作者：
M. Guo;Y. Zhang;X. K. Zhang;J. Zhang;L. Zhuang
采用差示扫描量热法（DSC）、硬度测量和高分辨透射电镜（TEM）研究了不同Zn含量的Al-Mg-Si-Cu合金的非等温析出行为。结果表明，Zn对Al-Mg-Si-Cu合金GP区的溶解和析出有显著影响。活化能随Zn含量和时效条件的变化而变化。添加0.5wt%或3.0wt%的Zn可以改善沉淀动力学，而添加1.5wt%的Zn则抑制沉淀动力学。Al-Mg-Si-Cu合金在加热到250 °C后仍以Mg-Si析出相（GP区和β″）为主，添加Zn后由于Mg-Zn析出相的逆转，没有观察到Mg-Zn析出相。实测的合金时效硬化响应与所建立的析出动力学方程的预测结果相一致。此外，添加3.0wt%Zn的预时效合金在人工时效过程中出现了硬度双峰现象，这是由于预β″和β″相的形成所致。最后，根据合金的微观组织演变和Mg、Si、Zn原子间的相互作用力，提出了不同Zn含量的Al-Mg-Si-Cu合金的析出机制。
The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.