Abstract Considering the interactions between solute atom (Li or Sn) and various surfaces, along with the ones between solute atoms in the surfaces, this work applies the first-principles method to investigate the influences of solute atoms on the surface energy of dilute Al alloys at room temperature, and further predicts the nano-crack nucleation along different surfaces. The statistical ordered surface configurations are depicted for ensuring the maximum surface concentrations of solute-atom segregations. The Gaussian-Like distribution (GLD) model is introduced to describe the distribution of solute atoms. Results indicate that the nano-crack nucleation may occur along the ( 1 ¯ 10 ) surface in the region of dilute Li atom less than 0.016%, but along the ( 1 ¯ 11 ) surface in the region of high concentration exceeding 0.016%. While Sn atom has a fairly stronger effect on reducing the surface energy than Li atom, especially in the ( 001 ) surface, suggesting that the nano-cracks are likely to nucleate along ( 001 ) surface under the action of Sn atom. This work provides a valuable guidance for theoretical and experimental study of the nano-crack nucleation in Al alloys.

中文翻译：

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第一性原理计算的溶质偏析对稀Al-X（X = Li，Sn）合金表面性能的影响

摘要 考虑溶质原子（Li 或 Sn）与各种表面的相互作用，以及表面溶质原子之间的相互作用，本工作采用第一性原理方法研究了溶质原子对稀铝合金表面能的影响。在室温下，并进一步预测沿不同表面的纳米裂纹成核。描述了统计有序表面配置以确保溶质原子分离的最大表面浓度。引入类高斯分布 (GLD) 模型来描述溶质原子的分布。结果表明，在稀Li原子浓度小于0.016%的区域，纳米裂纹形核可能沿(1~10)面发生，而在浓度超过0.016%的高浓度区域，则沿(1~11)表面发生纳米裂纹形核。而Sn原子对降低表面能的作用比Li原子更强，尤其是在（001）表面，表明纳米裂纹在Sn原子的作用下很可能沿（001）表面成核。该工作为铝合金纳米裂纹形核的理论和实验研究提供了有价值的指导。