Modulation of precipitation behavior by dislocations and alloying for superior strength-ductility balance in Al-Cu-Li alloys

• Published in: Journal of alloys and compounds 2025-01, Vol.1010, p.177334, Article 177334
• Main Authors: Xie, Yuankang, Liu, Shengdan, Guo, Xiaobin, He, Xiyu, Liang, Chaojie, Deng, Yunlai
• Format: Article
• Language: English
• Subjects: Al-Cu-Li alloys; Dislocation; Precipitation; Rolling; Strengthening
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.177334

Conventional T8 heat treatment makes it difficult to achieve the strength and ductility trade-off of Al-Cu-Li alloys, and a feasible strategy to overcome this challenge in this work. Analyzing the microstructures and properties of different aging treatments shows that the transition of sliding dislocation from shear to difficult shear precipitates with increasing T1 phase size is a major factor in reducing ductility. Effective control of the size of the T1 phase was achieved by utilizing high dislocation density-assisted heterogeneous nucleation and simultaneous assisted diffusion means combined with precipitation competition between the S′ and T1 phases. Dislocation and alloying to tightly control precipitation after aging, the yield strength (650 MPa) is significantly higher than that of T6 and T85 heat-treated alloys (150 MPa and 30 MPa), and most notably, the elongation reaches 13 %. As a consequence, this study is of great significance for the development of high-performance Al-Cu-Li alloys for aerospace applications. •Al-Cu-Li alloys with different alloying were thermo-mechanically processed to achieve an excellent strength-ductility balance.•The mechanical properties of Al-Cu-Li alloys with high dislocation density are closely related to the aging regime.•Dislocation and alloying to tightly control precipitation after aging significantly improves strength and ductility.