Achieving high strength and good laser welding performance by adding Sc to T8-aged Al-Cu-Li alloys with different Cu/Li ratios

Achieving high strength and good laser welding performance by adding Sc to T8-aged Al-Cu-Li alloys with different Cu/Li ratios

In this work, the effects of Sc addition and variations in the Cu/Li ratio on the microstructure, precipitation behavior, laser welding performance, and mechanical properties of Al-Cu-Li alloys were systematically investigated. The results show that the addition of Sc refines as-cast grains, transfo...

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Bibliographic Details
Main Authors: Changlin Li, Xiwu Li, Yongan Zhang, Kai Wen, Lizhen Yan, Ying Li, Yanan Li, Mingyang Yu, Guanjun Gao, Hongwei Yan, Zhihui Li, Baiqing Xiong
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Materials & Design
Subjects:
Al-Cu-Li alloy
Sc element
Microstructure
Mechanical property
Laser welding performance
Online Access:http://www.sciencedirect.com/science/article/pii/S0264127525007051
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Summary:In this work, the effects of Sc addition and variations in the Cu/Li ratio on the microstructure, precipitation behavior, laser welding performance, and mechanical properties of Al-Cu-Li alloys were systematically investigated. The results show that the addition of Sc refines as-cast grains, transforming coarse columnar grains into fine equiaxed grains. In high Cu/Li ratio alloys, the addition of Sc leads to the formation of the W (AlCuSc) phase. Reducing the Cu/Li ratio alters the solidification sequence, favoring early precipitation of the Al2CuLi phase and inhibiting W phase formation. The addition of the Sc significantly increases the elongation, while the introduced W phase does not cause a significant decrease in the strength of the T8-aged alloy. A lower Cu/Li ratio reduces the T1 phase volume fraction, but the high density of δ′/GPI/δ′ composite phases compensates for the strength loss from T1 phase. The addition of the Sc element significantly refines the grain size of the welded joints and suppresses solidification and liquation cracks. Simultaneously, a large number of Al3(Sc, Zr) particles precipitate in the HAZ, enhancing the strength of the joints and reducing softening in this zone. The medium Cu/Li ratio alloy exhibits excellent overall mechanical properties and welding performance.
ISSN:0264-1275

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