Effect of low temperature aging on microstructure and mechanical properties of super-high strength aluminum alloy^①

来源期刊：中南大学学报(英文版)2006年第5期

论文作者：冯春 刘志义 宁爱林 曾苏民

文章页码：461 - 467

Key words：Al-Zn-Mg-Cu alloy; low temperature aging; microstructure; mechanical properties; silver

Abstract: The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al-12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0.166%Ag(alloy1), and Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr(alloy 2) were investigated. The results show that low temperature aging after promotive solution treatment can increase elongation without the loss of strength for the studied alloys. The optimum aging treatment (T6) for alloy 1 and alloy 2 is 100℃/80 h and 100℃/48 h, respectively. Compared with other heat treatment alloys, alloy 1 and alloy 2 show super-high tensile strength up to 753 MPa and 788 MPa, remaining 9.3% and 9.7% elongation under T6 condition, respectively. During aging, trace addition of Ag enhances the formations of GP zone and metastable phase, and stabilizes GP zone and metastable phase to a higher temperature. Trace addition of Ag prolongs the aging time of reaching the peak strength and delays over-aging condition of the alloy. However, trace addition of Ag promotes the formation of coarse constituent in the alloy and consumes hardening alloying elements of Zn and Mg. Moreover, the addition of the transition element Zr in 7000 series super-high alloy forms incoherent Al3Zr dispersoid which can serve as nucleation sites for nonuniform precipitation ofηphase during aging process. The higher the aging temperature, the greater the tendency for nonuniform precipitation ofηphase.

基金信息：the National High-Tech Research and Development Program of China