低温时效及微量Ag对超高强度Al-Zn-Mg-Cu

Effect of Low Temperature Aging and Trace Addition of Ag on Mechanical Properties of Super-high Strength Al-Zn-Mg-Cu Alloy

研究了热处理工艺对Al12.2%Zn2.48%Cu2.0%Mg0.15%Zr0.166%Ag(合金1)、Al9.99%Zn1.72%Cu2.5%Mg0.13%Zr(合金2)两种合金的组织与性能的影响。通过差热分析、金相组织观察、力学性能测试及EDS分析、SEM形貌观察,分析了两种合金的微观组织和力学性能的变化规律。结果表明,采用强化固溶后低温时效工艺可使合金在保持高强度的同时,改善合金的塑性。合金1经100℃×80h时效后的峰值强度达到了753MPa以上,伸长率为9.3%;合金2经100℃×48h时效后的峰值强度达到了788MPa以上,伸长率为9.7%。合金1中微量Ag的加入会促进G.P.区和过渡相的形成,并提高过渡相的稳定性,使合金到达峰值的时间延长,延缓过时效。但是向合金中添加微量Ag会促进粗大相的形成,消耗了合金元素Zn、Mg。

The effect of heat treatment on the microstructure and mechanical properties of the two alloys, Al-12. 2% Zn- 2. 48% Cu-2. 0% Mg-0. 15% Zr-0. 166% Ag （ alloyl ）, and Al-9. 99% Zn-1.72% Cu-2. 5% Mg-0. 13% Zr （ alloy 2 ）, was investigated by tensile test, DTA and EDS analysis, OM and SEM observation. The results show that low temperature aging after strengthening solution can increase ductility without sacrifice of strength. After aging treatment of 100℃ × 80h for alloy 1 and 100℃ ×48h for alloy 2 obtained peak tensile strength of 753MPa and 788MPa,elongation of 9. 3% and 9. 7% ,respectively. Trace addition of Ag promoted the formation of G. P. zones and transition phases,enhanced the stability of transition phases, and prolonged the aging time reaching the peak value. However, trace addition of Ag to the alloy promotes the formation of coarse and consumes alloying elements Zn and Mg.