利用电化学阻抗谱(EIS)方法研究了Al-Zn-In-Mg-Ti合金阳极在3％ NaC1溶液中的腐蚀过程,观察了260 h浸泡腐蚀后的表面形貌.结果表明:合金腐蚀是点蚀引起的,腐蚀由钝化态开始,经点蚀诱导期,达到点蚀稳定期.分别采用不同等效电路拟合合金在不同腐蚀阶段的电化学阻抗谱.结果表明:当合金处于钝化态时,EIS谱为反应电阻Rt很大的容抗弧:随浸泡时间的延长,EIS谱低频出现感抗弧,合金进入点蚀诱导期,溶液电阻Rs增大,反应电阻Rt减小,蚀孔内反应电阻R0减小,感抗L收缩:合金处于点蚀稳定期时,EIS谱低频感抗弧消失,出现一直线,腐蚀产物扩散成为反应控制步骤.

The corrosion process of Al-Zn-In-Mg-Ti alloy in 3% NaCl solution was investigated with electrochemical impedance spectroscopy (EIS).The EIS was simulated using the equivalent circuit model.The EIS and surface corrosion morphology of the alloy showed that the pitting corrosion induced the alloy corrosion.The corrosion initiated from the passive film,and then the pitting corrosion from the inducement stage came to the stable stage.There was a big capacitive art of the reaction resistance Rt at high frequency at the passivation stage.At the inducement stage of pitting corrosion,there was an inductive art at the low frequency,while the solution resistance Rs increased,and the reaction resistance Rt and R0 in corrosion pit decreased and inductive L shriked.At the stable stage of pitting corrosion,the inductive art disappeared while a straight line appeared at the low frequency,the diffusion of corrosion product controlled the reaction process.