Chemical segregations at grain boundaries (GBs) have been broadly investigated in Al alloys. However, there are limited experimental evidence demonstrating the dependence of solute segregation on GB characteristics. Here, we quantified solute segregation at GBs in nanocrystalline Al-1Mg (at.%) alloy by combining energy-dispersive X-ray spectroscopy, high-resolution scanning transmission electron microscopy and automated crystallographic indexing and orientation mapping. The dependence of solute segregation on the grain boundary misorientation angle is analyzed. Due to their higher excess free volume, high angle grain boundaries contain more Mg solutes than the low angle grain boundaries. Furthermore, coherent twin boundaries (CTBs) exhibit low solute segregation. However, incoherent twin boundaries (ITBs) display greater solute concentration. The different solute segregation behavior between CTBs and ITBs originates from their grain boundary structure. The solute segregation behavior reported here may shed light on the GB engineering of Al alloys.

中文翻译：

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纳米晶铝镁合金中的晶界和孪晶界溶质偏析

铝合金中晶界 (GB) 处的化学偏析已得到广泛研究。然而，只有有限的实验证据表明溶质分离对 GB 特性的依赖性。在这里，我们通过结合能量色散 X 射线光谱、高分辨率扫描透射电子显微镜以及自动晶体学索引和取向映射，量化了纳米晶 Al-1Mg (at.%) 合金中 GB 处的溶质偏析。分析了溶质偏析对晶界取向差角的依赖性。由于其较高的过剩自由体积，高角度晶界比低角度晶界含有更多的镁溶质。此外，相干孪晶边界（CTB）表现出低溶质偏析。然而，不相干孪生边界 (ITB) 显示出更高的溶质浓度。CTB 和 ITB 之间不同的溶质偏析行为源于它们的晶界结构。这里报道的溶质偏析行为可能会对铝合金的国标工程有所启发。