Precipitation strengthening and strain hardening after pre-deformation in low Mg Al–Cu–Li alloys dominated by T phases have been widely studied in recent years due to their excellent mechanical properties. In this study, the aging precipitation behavior and the associated strengthening mechanisms caused by the increasing dislocation density in high Mg Al–Cu–Li alloys were systematically studied. The results showed that the dislocation density change along with the degree of the pre-stretching as well as the precipitation behavior, that is the pre-stretched methods inhibit the development of GPB zones and reduce the total precipitation of T phases to promote the development of S phases. Finally, the fraction of recrystallized zones decreases from 59.3% to 2.8% while the average KAM value increases from 0.62 to 1.40, and the yield strength increases from 500 MPa to 620 MPa. The overall precipitation strengthening increment in the case of multi-phase coexistence is essentially independent of dislocation density, which is mainly a result of the decrease in the strengthening increment for T phases is compensated by the strengthening increment for S phases. Our study is expected to provide theoretical contributions to the development of high-strength and high-toughness Al–Cu–Li alloys.

中文翻译：

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通过预拉伸和时效硬化相结合开发含镁超高强度 Al-Cu-Li 合金

以T相为主的低镁Al-Cu-Li合金由于其优异的力学性能，近年来得到了广泛的研究，其中预变形后的沉淀强化和应变硬化得到了广泛的研究。在这项研究中，系统地研究了高镁铝-铜-锂合金中位错密度增加引起的时效析出行为和相关强化机制。结果表明，位错密度随着预拉伸程度以及析出行为的变化而变化，即预拉伸方法抑制了GPB区的发展，减少了T相的总析出，促进了T相的发展。 S 阶段。最终，再结晶区比例从59.3%下降到2.8%，平均KAM值从0.62增加到1.40，屈服强度从500 MPa增加到620 MPa。多相共存情况下的总体析出强化增量基本上与位错密度无关，这主要是T相强化增量的减少被S相强化增量补偿的结果。我们的研究有望为高强度和高韧性Al-Cu-Li合金的开发提供理论贡献。