热处理工艺对超高强铝合金组织与性能的影响

The Effect of Heat Treatment on Microstructure and Mechanical Properties of Ultra High Strength Aluminum Alloy

通过硬度、拉伸性能测试 ,金相、扫描电镜、透射电镜观察 ,X射线衍射分析 ,研究了热处理工艺对新型电磁铸造合金 (Al 9.0Zn 2 .5～ 2 .8Mg 2 .0～ 2 .4Cu 0 .1～ 0 .15Zr 0 .2 2 4Ag)显微组织和性能的影响。结果表明 :合金的峰时效制度为 12 0℃ / 2 4h。在峰时效条件下 ,合金的抗拉强度达到 73 0MPa ,屈服强度达到 70 5MPa ,延伸率为 8.8%。合金有显著的时效硬化特性 ,其强化机制主要是沉淀强化 ,合金的主要强化相为GP区和 η′过渡相。合金的断裂形式为微孔聚集型韧性断裂。

An Al-9.0Zn-2.5～2.8Mg-2.0～2.4Cu-0.1～0.15Zr-0.2～0.25Ag Ultra high strength aluminum alloy was prepared by low frequency electric-magnetic casting process, The microstructure and mechanical properties of the alloy under different treatment conditions was investigated by tensile properties and hardness test, SEM, TEM observations and XRD analysis. The results show that the peak aging occurred at 120 ℃ for 24 h. Under the peak-ageing condition, the tensile strength, yield strength and elongation of the studied alloy was 730 MPa, 705 MPa and 8.8%, respectively. The main strengthening mechanism of the alloy was precipitation hardening and the strengthening phase was GP zone and η′(MgZn 2).