微量Zn对Al-Cu-Li-Mg合金时效特性与微观组织的影响

通过时效硬化效应的测试和微观组织的透射电镜分析, 研究了不同含量Zn 对Al-Cu-Li-Mg 合金时效特性与微观组织的影响。研究结果表明:少量Zn 的添加增强了合金的时效硬化效应, 但延缓了峰值时间的到来, 且随Zn 含量的增加, 该作用越显著。合金时效硬化曲线上出现2 个硬化峰, 第一阶段的硬化峰是由于δ′的早期析出所致, 第二阶段的硬化峰是由于δ′和T1 以及含Zn 相共同作用所致。Zn 的添加具有两方面的作用:① 降低了Li 在Al 中的溶解度, 增加了与基体的错配度, 从而促进了δ′的析出;② Zn作为很强的空位陷阱对空位的束缚作用, 从而抑制了析出相的长大。

Effects of Small Additions of Zinc on Aging Characteristics and Microstructure of Al-Cu-Li-Mg Alloy

The effects of Zinc with different content on aging characteristics and microstructure of Al-Cu-Li-Mg alloy have been investigated by measuring age hardening curves and observing with transmission electron microscope .Results indicate that small addition of Zn can strengthen the aging hardening effects of Al-Cu-Li-Mg alloy , putting off the aging peaks .Such function will become more and more strong as the increase in the addition of Cr .There were two hardening peak in alloy age hardening curve .The first stage of age hardening peak is attributed to the precipitation of δ′and the second stage is due to the precipitation of δ′, T1 and Zn-containing precipitates .The addition of Zn can result in the followings :① The precipitation of δ′ was stimulated by reducing the solubility of Li in Al and increasing the mismatch between Li andmatrix ;②The growth of precipitated phase was restrained owing to the strong ability of Zn to bound vacancy as vacancy trap .