(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 通过常规拉伸性能测试、扫描电镜(SEM)和透射电镜(TEM)观察，研究少量Mg、Ag、Zn多元微合金化对一种新型Al-Cu-Li合金微观组织与拉伸性能的影响。结果表明：在T6、T8时效态下，该合金的抗拉强度(σb)和屈服强度(σ0.2)均大于不含Mg、Ag、Zn的另外3种合金的，而伸长率(δ)相差较小。其主要强化析出相为大量的T1相、部分θ′相和少量的S′相。在T6时效态下，Mg、Ag的同时存在大大促进T1相和S′相的析出，显著增加合金强度；Mg、Zn的同时添加也促进T1相和S′相的析出，使合金强度在一定程度上得到提高。Mg元素微合金化的强化效果最强，同时添加Ag和Zn或单独添加Ag或Zn均能增强其强化效果；无Mg存在条件下，添加Ag、Zn对合金的强化效果较小。在T8时效态下，时效前的预变形形成的大量位错成为T1相的形核点，使合金形成细小、密集和均匀弥散分布的T1相，削弱了Mg、Ag、Zn元素对合金时效析出过程的影响。
关键字: Mg；Ag；Zn；Al-Cu-Li合金；拉伸性能；微观组织
（School of Materials Science and Engineering, Central South University, Changsha 410083，China）
Abstract:The effects of Mg, Ag and Zn multi-alloying on tensile properties and microstructure of a new Al-Cu-Li alloy were investigated by means of tensile test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the tensile strength (σb) and yield strength (σ0.2) of the new Al-Cu-Li alloy are higher than those of the three alloys without Mg, Ag and Zn, respectively, while the elongation (δ) is almost the same in T6 and T8 temper. The main strengthening phases are plenty of T1 phase, part of θ′ phases and a little of S′ phase. In T6 temper, the additions of Mg and Ag accelerate the precipitation of T1 and S′ phase which improves the strength prominently. Mg and Zn also accelerate the precipitation of T1 and S′ phases, which improve the strength to some extent. The microalloying of Mg shows the strongest strengthening effect, while adding both of Ag and Zn or adding Ag or Zn separately can enhance the strengthening effect of Mg. Without the presence of Mg, the additions of Ag and Zn have little effect on the strengthening. In T8 temper, the predeformation before aging forms plenty of dislocations which become the precipitation sites of T1 phase, making finer, dense and uniform T1 phase in the matrix, which weakens the effects of Mg, Ag and Zn on the aging behavior of the new Al-Cu-Li alloy.
Key words: Mg; Ag; Zn; Al-Cu-Li alloy; tensile property; microstructure
