Effect of aging time on microstructure and glossiness of anodized film on surface of Al-Mg-Si-Cu aluminum alloy

The anodic oxide film was prepared on surface of Al-Mg-Si-Cu alloy by sulfuric acid anodic oxidation. The alloy was aged at 180 ℃ for 4 h, 10 h and 30 h, respectively. The effect of different aging time treatment on the microstructure and glossiness of the anodic oxide film of Al-Mg-Si-Cu alloy was investigated. The results show that the glossiness of different samples decreases significantly after anodic oxidation compared with the matrix material, and the glossiness increases first and then decreases with the increase of aging time. With the increase of aging time, the grain boundary precipitates present continuous−discrete−continuous states, which are preferentially oxidized and dissolved during the anodic oxidation process, leaving holes along the grain boundary. The holes caused by the continuous grain boundary precipitates are more obvious, and the roughness of the pores and their surrounding areas increases, which is the main reason for the difference of gloss after anodic oxidation of the alloy with different aging time. The coarse AlFeMnSi phase in the matrix will cause micron-sized holes in the anodic oxidation film and reduce the gloss of the sample and the aging time has little effect on this phase. © 2024 Central South University of Technology. All rights reserved.