We conducted electrochemical experiments on 5083 aluminum alloy with different microstructures and measured the samples before and after corrosion by SEM and EBSD. At the same time, density functional theory was used to calculate the chloride ion adsorption behavior of the Mg₂Al₃ phase, which explained the corrosion mechanism on a multi-scale. The results indicated that edge and heart specimens with varying grain sizes exhibited different trends post heat treatment. Specifically, increasing temperature led to larger grain sizes in the heart region, while smaller grain sizes were observed at the edge. Furthermore, the quantity of the second phase was higher after heat treatment at 550 °C compared to 520 °C. The grain size affects the densification of the passivation film and the potential difference between the second phase and the substrate, leading to variations in corrosivity. Density functional theory calculation demonstrates that the Mg₂Al₃ (001)MgAl and (001)Al surfaces exhibit higher susceptibility to Cl⁻ adsorption, showing the lowest adsorption energies of Cl⁻ at the Mg-top of (001)MgAl and Al-top sites of (001)Al. A stronger bond between Cl⁻ and Mg atoms leads to intergranular corrosion in different directions.

中文翻译：

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不同微观结构的 5083 铝合金在 NaCl 环境中的电化学行为和腐蚀机理的多尺度研究


我们对具有不同微观组织的 5083 铝合金进行了电化学实验，并通过 SEM 和 EBSD 测量了腐蚀前后的样品。同时，采用密度泛函理论计算了 Mg₂Al₃ 相的氯离子吸附行为，从多尺度上解释了腐蚀机理。结果表明，不同晶粒大小的边缘和心形试样在热处理后表现出不同的趋势。具体来说，温度升高导致中心区域的晶粒尺寸较大，而在边缘观察到较小的晶粒尺寸。此外，与 520 °C 相比，在 550 °C 下热处理后第二相的数量更高。 晶粒尺寸会影响钝化膜的致密化以及第二相与基材之间的电位差，从而导致腐蚀性发生变化。密度泛函理论计算表明，Mg₂Al₃ （001）MgAl 和 （001）Al 表面对 Cl⁻ 吸附表现出更高的敏感性，在 （001）MgAl 的 Mg-top 和 （001）Al 的 Al-top 位点显示出 Cl⁻ 的最低吸附能。Cl⁻ 和 Mg 原子之间较强的键会导致不同方向的晶间腐蚀。