Microstructure and mechanical properties of Mg,Ag and Zn multi-microalloyed Al-(3.2-3.8)Cu-(1.0-1.4)Li alloys

Mg、Ag、Zn多元复合微合金化Al-(3.2~3.8)Cu-(1.0~1.4)Li合金的显微组织和力学性能（英文）

To develop super-high strength Al-Li alloy,the microstructures and mechanical properties of Mg,Ag and Zn microalloyed Al-（3.2-3.8）Cu-（1.0-1.4）Li alloys（mass fraction） with T8 temper were studied.The results showed that 1%of lower Li content restricted the strengthening effect of increasing Cu content,while simultaneous increase in Cu and Li contents contributed effectively to the enhancement of strength.The alloys were mainly strengthened by plenty of fine and well dispersed TI（Al2CuLi）precipitates.There were also some minor precipitates of θ＇（Al2Cu） and δ＇（Al3Li）,which became less in number density,even disappeared during the aging process.Meanwhile,higher Li content favored the formation θ＇ and δ＇ and a small amount of S＂（Al2CuMg） phases.In addition,strengthening effect and microstructure variation were analyzed through total non-solution mole fraction of Cu and Li and their mole ratio.To obtain Al-Li alloy with super-high strength,the total mole fractions of Cu and Li should be increased,and their mole ratios should also be kept at a certain high level.

为开发新型超高强铝锂合金,研究T8态时效处理的Mg、Ag、Zn复合微合金化Al-（3.2-3.8）Cu-（1.0-1.4）Li合金的显微组织及力学性能。结果表明,Li含量较低（1.0%）时,通过增加Cu含量来提高铝锂合金强度的作用有限,而同时增加Cu和Li含量则有利于其强度的明显提高。铝锂合金的主要强化相为大量细小弥散的T1（Al2CuLi）相;同时,合金中还析出少量θ＇（Al2Cu）相及δ（Al3Li）相,而且随时效过程的进行,其密度降低,甚至消失。Li含量较高时有利于δ＇相及θ＇相的形成,并可能导致形成少量S＇（Al2CuMg）相。另外,采用非固溶Cu、Li原子的总摩尔分数及其比例分析Cu、Li含量变化对合金强化效果及显微组织的影响。为获得超高强度的铝锂合金,一方面需提高Cu、Li原子的总摩尔分数,另一方面也应维持其较高比例。