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Ageing Processes of Li-Containing Al-Zn-Mg-Cu Alloys

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Abstract:

1.1%Li was added to 7075 alloys to obtain the Li-containing Al-Zn-Mg-Cu alloys. The microstructure and hardness of the alloys are investigated by transmission electron microscopy (TEM) and Vickers hardness. The hardness of the single-aged alloys is low. When the alloys were double-aged or multi-aged, the hardness is comparable to that of Al-Zn-Mg-Cu alloys at peak ageing. Two peaks were present in the hardness curves of the multi-aged Li-containing Al-Zn-Mg-Cu alloys. With the last-step temperature increases, two-peak phenomenon becomes prominent. The density and size of precipitates are influenced remarkedly by the ageing processes. Coarse grain boundary precipitates and PFZ (precipitate free zone)can be observed when the Li-containing Al-Zn-Mg-Cu alloys were multi-aged, and the higher the last-step ageing temperature, the wider the PFZ is.

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Periodical:

Key Engineering Materials (Volumes 353-358)

Pages:

1605-1608

DOI:

https://doi.org/10.4028/www.scientific.net/KEM.353-358.1605

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Online since:

September 2007

Authors:

Zhong Kui Zhao, Tie Tao Zhou, Pei Ying Liu, Chang Qi Chen

Keywords:

Aging Process, Hardness, Li-Containing Al-Zn-Mg-Cu Alloy, Precipitation

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© 2007 Trans Tech Publications Ltd. All Rights Reserved

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References

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