( 中南大学 材料科学与工程学院， 长沙 410083)
摘 要: 研究了2195铝锂合金在不同时效状态下的晶间腐蚀和剥落腐蚀行为。结果表明： 2195合金在自然时效状态下具有较好的抗晶间腐蚀和剥落腐蚀能力，但随着在160℃时效时间的延长， 其晶间腐蚀与剥落腐蚀倾向逐渐增加；在剥落腐蚀溶液中进行的极化曲线测试也表现出相同的趋势。 透射电镜观察发现： 2195合金主要析出相为T1相； 随着时效时间延长， T1相逐渐粗化， 在晶界处还会出现无析出带及平衡相。模拟相实验证实， 由于T1相和无析出带的开路电位都明显低于铝基体的，在腐蚀性介质中作为阳极相优先溶解， 从而导致2195合金产生晶间腐蚀及剥落腐蚀。过时效状态与峰时效状态相比， 晶界平衡相增多， 无析出带变宽， 晶间腐蚀及剥落腐蚀程度将更加严重。
关键字: Al-Li合金；时效； 腐蚀； 电化学
（ School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: Intergranular corrosion and exfoliation corrosion behavior of 2195 Al-Li alloy with different aging treatment schemes were studied. The results show that the naturally-aged 2195 alloy has the best intergranular and exfoliation corrosion resistance. The intergranular and exfoliation corrosion are accelerated with prolonging the increasing aging time at 160℃, which is in accord with the results of polarization tests in IGC solution. Microstructure observations show that the main precipitate of 2195 Al-Li alloy is T1 phase. With the aging time increasing, T1 phase coarsens, and precipitate-free-zone(PFZ) and equilibrium phases are observed along grain boundaries. It is shown by open-circuit potential measurements that the open-circuit potentials of PFZ and T1 phase are more negative than that of Al matrix. They act as anodes in corrosive media and dissolve preferentially. These cause the intergranular and exfoliation corrosion of 2195 alloy. Compared with the peak-aged alloy, the over-aged alloy contains more equilibrium phases at the grain boundaries and wider PFZ, and thus suffers from faster intergranular and exfoliation corrosion.
Key words: Al-Li alloy; aging; corrosion; electrochemistry
