扫描电化学显微镜技术原位测Al-Mg合金在3.5％NaCl+5 mmol/L KI溶液中的腐蚀特性

摘要

The corrosion behavior of Al-Mg alloy in 3.5wt.％ NaCl + 5 mmol/L KI solution was investigated by scanning electrochemical microscopy (SECM).The surface morphology of the samples was observed by optical microscopy.The component of intermetallic compound was analyzed by scanning electron microscopy and energy dispersive spectroscopy.The corrosion mechanism of Al-Mg alloy was studied preliminarily.The results show that the dissolution was different in different regions of the surface of Al-Mg alloy,and the corrosion mainly occurred in the interface between intermetallic compounds and Al matrix.The quantity and value of oxidation peak current on the surface of Al-Mg alloy changed with prolongation of corrosion time,indicating that the surface dissolution was uneven in corrosion process.The intermetallic compounds were dissolved by corrosion first,and the corrosion pits appeared obviously after corrosion for 144 hours.%采用扫描电化学显微镜技术研究了Al-Mg合金在3.5％ NaCl(质量分数)+5 mmol/L KI溶液中的腐蚀行为,利用光学显微镜观察腐蚀后试样的表面形貌,用扫描电镜和能谱仪分析合金内金属间化合物成分,初步探讨Al-Mg合金的腐蚀机理.结果表明:Al-Mg合金表面不同区域活性溶解度不同,且腐蚀主要发生在金属间化合物与基体铝界面处;Al-Mg合金表面氧化电流峰的数量和数值随腐蚀时间延长而不断变化,说明在腐蚀过程中基体表面溶解是不均匀的,金属间化合物优先被腐蚀,144 h后出现明显腐蚀坑.