时效时间对Al-Mg-Si-Cu铝合金表面阳极氧化膜微观结构及光泽度的影响

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

采用硫酸阳极氧化对经过180℃下4 h、10 h、30 h时效处理的Al-Mg-Si-Cu合金表面进行阳极氧化处理,探究不同时效时间对Al-Mg-Si-Cu合金阳极氧化膜层微观结构及其光泽度的影响。研究结果表明:与基体材料相比,不同时效时间合金阳极氧化后的光泽度均出现明显降低,且光泽度随时效时间增加先变大后减小;随时效时间增加,合金晶界析出相分别呈现连续—离散—连续的分布状态,其在阳极氧化过程中优先氧化溶解,使阳极氧化膜呈现沿晶界分布的孔洞特征,连续分布的晶界析出相引起的孔洞更明显,同时造成孔洞及其周围区域粗糙度增加,这是不同时效时间合金阳极氧化后光泽度出现差异的主要原因;基体中粗大的AlFeMnSi相会出现阳极氧化膜层中微米级孔洞,从而降低阳极氧化样品的光泽度,但时效时间对其没有明显影响。

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.