State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China.
School of Material Science and Engineering/Herbert Glitter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing, 210094, China.
Nat Commun. 2023 May 23;14(1):2959. doi: 10.1038/s41467-023-38730-z.
High strength aluminum alloys are widely used but their strength is reduced as nano-precipitates coarsen rapidly in medium and high temperatures, which greatly limits their application. Single solute segregation layers at precipitate/matrix interfaces are not satisfactory in stabilizing precipitates. Here we obtain multiple interface structures in an Al-Cu-Mg-Ag-Si-Sc alloy including Sc segregation layers, C and L phases as well as a newly discovered χ-AgMg phase, which partially cover the θ' precipitates. By atomic resolution characterizations and ab initio calculations, such interface structures have been confirmed to synergistically retard coarsening of precipitates. Therefore, the designed alloy shows the good combination of heat resistance and strength among all series of Al alloys, with 97% yield strength retained after thermal exposure, which is as high as 400 MPa. This concept of covering precipitates with multiple interface phases and segregation layers provides an effective strategy for designing other heat resistant materials.
高强度铝合金被广泛应用，但在中高温下纳米析出相迅速粗化会导致其强度降低，这极大地限制了它们的应用。在沉淀相/基体界面处的单溶质偏析层在稳定沉淀相方面并不令人满意。在这里，我们在 Al-Cu-Mg-Ag-Si-Sc 合金中获得了多种界面结构，包括 Sc 偏析层、C 和 L 相等，以及新发现的 χ-AgMg 相，它们部分覆盖了 θ'沉淀相。通过原子分辨率的特性和从头算计算，已经证实了这种界面结构可以协同延缓沉淀相的粗化。因此，设计的合金在所有 Al 合金系列中表现出良好的耐热性和强度结合，热暴露后屈服强度保留率高达 97%，高达 400MPa。这种用多种界面相和偏析层覆盖沉淀相的概念为设计其他耐热材料提供了一种有效的策略。
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