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系统研究了2099铝锂合金晶间腐蚀行为与时效制度(T6态150和175℃时效、T8态150℃时效)的相关性,建立了2099铝锂合金腐蚀-时效进程状态图。结果表明,时效过程按腐蚀类型变化可以分为4个阶段。时效早期发生孔蚀或局部晶间腐蚀,欠时效阶段发生全面晶间腐蚀,近峰时效阶段转变为局部晶间腐蚀,过时效阶段以孔蚀为主。欠时效时,细小的晶界析出相连续分布,晶间腐蚀敏感性较高。过时效阶段晶界析出相粗化,并呈不连续分布,抗晶间腐蚀能力提高。时效温度提高,晶界析出相粗化,析出相间距增加,而时效前预变形能够促进析出相均匀弥散形核,抑制晶界无沉淀带形成,因而导致晶间腐蚀欠时效阶段和近峰失效阶段的时效时间范围缩短或消失,提高了抗晶间腐蚀能力。
The relationship between the intergranular corrosion behavior of 2099 Al-Li alloy and the aging system (T6 150 and 175 ℃ aging, T8 150 ℃ aging) was systematically studied, and the state diagram of corrosion-aging process of 2099 Al-Li alloy was established. The results show that the aging process can be divided into four stages according to the type of corrosion. Pitting corrosion or local intergranular corrosion occurs early in the aging process, and full intergranular corrosion occurs in the under-aging stage, and the near-peak aging stage changes to local intergranular corrosion. Pitting corrosion mainly takes place in the over-aging stage. Under-aging, the fine grain boundary precipitation continuous distribution of intergranular corrosion sensitivity. The grain boundary precipitated phase is coarsening and appears discontinuous in the over-aged stage, improving the intergranular corrosion resistance. Aging temperature increases, grain boundary precipitation coarsening precipitation phase spacing increases, and pre-aging pre-deformation can promote precipitation of uniform dispersed nucleation, inhibition of the grain boundary without the formation of precipitation zone, which led to intergranular corrosion under-aging stage and the near-peak failure Phase of the aging time range shortened or disappeared, improved resistance to intergranular corrosion.