The Evolution of the Clusters and Precipitates in Al-Cu-Mg Alloys

XL Xu and DH Li and KM Sun and RH Kou, TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS, 78, 191 (2025).

DOI: 10.1007/s12666-025-03660-5

In this study, the evolution of the clusters (Cu-Cu pairs and Cu-Mg pairs) and precipitates (Al2Cu and Al2CuMg) in the Al-Cu-Mg alloy has been investigated by first-principle calculations. The results show that Cu and Mg atoms prefer to form Cu-Cu pairs, but the Mg atoms present stronger moving ability than the Cu atoms. Hence the Cu-Mg pairs are easier to form during normal aging treatment, but the Cu-Cu pairs are more stable during a long time aging treatment. These two type clusters are metastable and transform into more stable precipitate phases (Al2CuMg and Al2Cu). The Al2CuMg phase is most thermal stable among these two phases. Further analysis of electronic structures indicates that this should be attributed to the more bonding electron numbers below Fermi level of the Al2CuMg phase. These results offer further insight into the understanding of the precipitate evolution in the Al- Cu-Mg alloys.

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