7A04-T6铝合金中金属间化合物对其阳极氧化膜耐蚀性的影响

摘要

In order to study the effects of inter-metallic particles on the corrosion resistance of anodic films on 7A04-T6 aluminium alloy,the metallographic microstructure of hot extrusion rod of 7A04-T6 aluminium alloy was observed by scanning laser confocal microscopy.The inter-metallic particles were identified by backscattered electron image. The morphologies of the areas with inter-metallic particles were traced before and after anodization and after immersion in exfoliation corrosion liquid for different times.The electrochemical impedance spectroscopy (EIS)was measured.The results indicated that the cavities caused by larger inter-metallic particles in the anodic films on 7A04 aluminium alloy were responsible for the corrosion beneath anodic films,the cracking and final complete failure of anodic films.%为研究7A04-T6铝合金中金属间化合物对其阳极氧化膜耐蚀性的影响，采用激光共聚焦显微镜对热挤压7A04-T6铝合金棒材不同方向截面的金相组织进行观察，并借助背散射和能谱鉴别组织中尺寸较大的金属间化合物颗粒，然后观察试样上含有金属间化合物区域在阳极氧化前、后和腐蚀不同时间后的形貌，并对腐蚀不同时间后的试样进行电化学阻抗谱（EIS）测试。结果表明，7A04-T6铝合金中尺寸较大的金属间化合物颗粒导致的阳极氧化膜孔洞是阳极氧化膜底部腐蚀、氧化膜破裂和最终完全失效的原因。