Uncovering the origin of enhanced strengthening in Li-added Al-Cu-Mg alloys
Uncovering the origin of enhanced strengthening in Li-added Al-Cu-Mg alloys
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揭示添加锂的 Al-Cu-Mg 合金强化强化的根源
DOI：
10.1016/j.msea.2021.142079
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发表时间：
2021-09-20
期刊：
影响因子：
6.4
通讯作者：
Liu, F.
中科院分区：
文献类型：
--
作者：
Duan, S. Y.;Huang, L. K.;Liu, F.
微量元素的添加对于通过改变沉淀来设计高强度铝合金是有效的，因此澄清强化起源具有非常重要的意义。在此，在 Al-Cu-Mg 合金（AA2024 合金）中添加 0.5 wt% Li，与对应的无 Li 合金相比，未拉伸和拉伸合金均在不降低延展性的情况下实现了强度的明显增加。添加Li引起的强度增强主要与Guinier-Preston-Bagaryatsky (GPB)区和S相的沉淀行为改变有关（而不是Li元素引起的溶质强化）；然而，未拉伸和拉伸合金的强化源是根本不同的。相关表征表明，对于峰值时效（PA）状态的未拉伸合金，添加Li有利于均匀分布的高密度GPB区，同时抑制S相析出物的成核。而对于 PA 状态的拉伸合金，Li 添加与 T1 相可能的强化相结合，导致细化的 S 相沉淀物。这些改性沉淀物（GPB 区和 S 相）被 Li 富集修饰，这被认为与所提出的 Li-空位复合体机制相关。因此，阐明添加锂的 Al-Cu-Mg 合金在未拉伸和拉伸条件下的强化起源，有望为其他高强度铝合金中添加 Li 作为微量元素时的强化机制提供基本见解。
The addition of minor elements is effective in designing high-strength aluminum alloys by modifying precipitation, such that clarifying the strengthening origin is highly significant. Here, 0.5 wt% Li is added in an Al-Cu-Mg alloy (AA2024 alloy), where, obvious increases in strength without reducing the ductility are achieved in both the unstretched and stretched alloys, as compared to those in the counterpart Li free alloys. The enhanced strength arising from Li addition is mainly related to the modified precipitation behavior (rather than the solute strengthening due to Li elements), in terms of Guinier-Preston-Bagaryatsky (GPB) zones and S-phase; the strengthening sources in the unstretched and stretched alloys, however, are fundamentally different. Correlative characterizations reveal that, for the unstretched alloy in the peak-aging (PA) state, the Li-addition favors a high density of uniformly distributed GPB zones while suppressing the nucleation of S-phase precipitates. Whereas, for the stretched alloys in the PA state, the Li-addition, in combination with the possible strengthening due to the T1 phase, results in refined S-phase precipitates. These modified precipitates (GPB zones and S-phase) are decorated with Li enrichments, which are believed to be correlated with the proposed mechanism of the Li-Vacancy complex. Thus, elucidating the origin of strengthening in Li-added Al-Cu-Mg alloys under both unstretched and stretched conditions, is expected to provide basic insights into the strengthening mechanisms in other high strength Al alloys when Li is added as the minor element.