锂对低Cu/Mg比Al-Cu-Mg-Ag合金时效特性的影响

通过时效硬化曲线的测量、室温拉伸实验以及时效组织的电镜观察,研究了添加锂对低Cu/Mg比Al-Cu-Mg-Ag合金时效特性的影响.结果表明,在Al-4.0Mg-1.5Cu-0.4Ag合金中添加锂,可以加速合金的时效进程,但其时效硬化效果并不能简单地随着含锂量的增加而逐步加强,只有当锂含量达到2.0%(质量分数)时,才表现出显著的时效硬化与强化效果.含2.0%Li的A1-4.0Mg-1.5Cu-0.4Ag合金中Z相、δ′以及δ′/β′复合粒子的弥散析出是产生显著时效硬化与强化的原因.

Influence of Li on the ageing characteristics and microstructure of Al--Cu--Mg--Ag alloy with low Cu/Mg ratio

The influence of lithium on the ageing behavior and microstructure of the low Cu/Mg ratio Al--Cu--Mg--Ag alloys was investigated. The results show that the effect of Li is to increase the rate of hardening, however, the addition of lithium does not progressively change age hardening and precipitation process of Al--Cu--Mg--Ag alloys with low Cu/Mg ratio, and significant age hardening response only occurs with the addition of 2.0\%Li (mass fraction). Transmission electron microscope (TEM) investigation results show that the remarkable increase of age hardness and strength is attributed to the fine dispersion of $\delta^{\prime}$, $Z$ phase and spherical $\delta^{\prime}$/$\beta^{\prime}$ compound particles in the 2.0\%Li--containing alloy.