Abstract Alkaline etching as an anodization pretreatment process is critical to structure and anticorrosion performance of the anodic film. The effects of modification by alkaline etching on AA6061 surface microstructure and corresponding film growth behaviors have been investigated in this work. The in-situ characteristics of grain boundaries, intermetallic particles and film structure were investigated. It is found that a suitable etching time can effectively remove a number of intermetallic particles and reduce the roughness from the matrix surface. For 60s etching, as the microstructures (e.g. cathodic Al-Fe-Si-Mn phase, grain boundary and anodic Al-Mg-Si phase) with different local potential from the matrix are modified, the growth rate can reach 0.39μm min−1 and the integrity of the anodic film are all increased. Extending etching time up to 120s will significantly disturb the regularity of pore order and reduce film growth rate because of the excessive corrosion at grain boundary.

中文翻译：

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碱蚀对Al-Mg-Si合金阳极膜组织和防腐性能的影响

摘要 碱蚀作为阳极氧化预处理工艺，对阳极氧化膜的结构和防腐性能至关重要。本工作研究了碱性蚀刻改性对 AA6061 表面微观结构和相应薄膜生长行为的影响。研究了晶界、金属间化合物颗粒和薄膜结构的原位特征。研究发现，合适的蚀刻时间可以有效去除大量金属间化合物颗粒，降低基体表面的粗糙度。对于 60s 蚀刻，由于与基体具有不同局部电位的微观结构（例如阴极 Al-Fe-Si-Mn 相、晶界和阳极 Al-Mg-Si 相）被修改，生长速率可达 0.39μm min-1并且阳极膜的完整性都增加了。