不同热处理态2024铝合金的腐蚀行为

摘要

分别在3.5%NaCl溶液、3.5%NaCl+1.0%H2O2溶液和pH=12的3.5%NaCl溶液中进行动电位极化实验，研究2024 Al-Cu-Mg合金在不同热处理状态下的腐蚀行为。极化曲线表明，随着合金时效时间的延长，合金的腐蚀电位向负方向移动；向NaCl溶液中添加H2O2会使腐蚀电位正移；在pH=12的3.5%NaCl溶液中的极化曲线表现出明显的钝化现象。腐蚀试样表面表现为常见的腐蚀特征，但也有扩大的点蚀、晶间腐蚀现象出现。循环动电位极化曲线显示有宽的循环极化滞后环，不同的腐蚀模式表明合金的点蚀生长对合金的热处理状态敏感。通过显微组织分析，探讨了不同热处理状态下合金在不同NaCl溶液中的腐蚀机理。%Corrosion behavior of 2024 Al-Cu-Mg alloy of different tempers was assessed by potentiodynamic polarization studies in 3.5% NaCl solution, 3.5% NaCl+1.0% H2O2 solution and 3.5% NaCl solution at pH 12. Polarization curves showed shifting of corrosion potential (φcor ) towards more negative potential with increasing ageing time and shifting ofφcor in the positive direction with the addition of H2O2 in NaCl solution. Polarization curves in 3.5% NaCl solution at pH 12 exhibited distinct passivity phenomenon. Optical micrographs of the corroded surfaces showed general corrosion, extensive pitting and intergranular corrosion as well. Cyclic potentiodynamic polarization curves exhibited wide hysteresis loop and the mode of corrosion attack confirmed that the alloy states are susceptible to pit growth damage. Attempts were made to explain the observed corrosion behavior of the alloy of various tempers in different electrolytes with the help of microstructural features.