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采用电化学阻抗谱(EIS)和电化学噪声(EN)方法研究回归再时效(RRA)热处理状态下7A60铝合金的点蚀行为,通过扫描电子显微镜(SEM)和能谱仪(EDS)观察和分析合金的组织和第二相颗粒成分。结果表明,7A60铝合金在3.5%Na Cl溶液中存在两个腐蚀阶段,并且可以用EIS出现两个电容时间常数的时间和由EN计算出的小波分形维数D的变化来表征。SEM和EDS分析结果表明,在7A60铝合金中,严重的点蚀主要是由阳极相Mg Zn2引起的,其次是Al2MgC u和Mg2Si相,Al7Cu2Fe相对7A60铝合金点蚀行为的影响不大。
The pitting corrosion behavior of 7A60 aluminum alloy under RRA heat treatment was investigated by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) methods. The corrosion behavior of 7A60 aluminum alloy was observed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) The microstructure of the alloy and the second phase grain composition were analyzed. The results show that there are two corrosion stages in 7A60 aluminum alloy in 3.5% NaCl solution and can be characterized by the time when EIS appears two capacitance time constants and the change of wavelet fractal dimension D calculated by EN. The results of SEM and EDS show that in 7A60 aluminum alloy, severe pitting corrosion is mainly caused by the anode phase Mg Zn2, followed by Al2MgCu and Mg2Si phases, and Al7Cu2Fe has little effect on the pitting corrosion of 7A60 aluminum alloy.