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采用硬度和电导率测试、差热分析、金相观察和电子显微分析方法,研究了均匀化过程中超高强Al-Zn-Mg-Cu-Zr合金硬度、电导率和显微组织的演变规律。结果表明:铸态合金主要由过饱和固溶体α(Al)及非平衡共晶组织组成。在300~490℃均匀化过程中,其显微组织发生了如下变化:一方面,η相和Al3Zr相的析出行为随着均匀化温度的改变而呈现出规律性的变化;另一方面,随着均匀化温度的升高,铸态合金的枝晶组织和枝晶间粗大的非平衡相逐步消失,其硬度先降低后升高,电导率先升高后降低,这种性能变化与组织结构变化一一对应。合金铸锭适宜的均匀化工艺为450℃保温24 h,均匀化过程动力学分析结果与实验结果基本吻合。
The hardness, electrical conductivity and microstructure evolution of ultra-high strength Al-Zn-Mg-Cu-Zr alloy during homogenization were investigated by hardness and conductivity tests, differential thermal analysis, metallographic observation and electron microscopy. The results show that as - cast alloy is mainly composed of supersaturated solid solution α (Al) and non - equilibrium eutectic structure. During the homogenization process at 300-490 ℃, the microstructure changes as follows: on the one hand, the precipitation behavior of η phase and Al3Zr phase changes regularly with the homogenization temperature; on the other hand, With the increase of the homogenization temperature, the coarse unbalanced phase of dendritic structure and dendrite of the as-cast alloy disappeared step by step. The hardness of the as-cast alloy decreased first and then increased, and the conductivity increased first and then decreased. The change of the properties and the structure of the alloy A correspondence. The suitable homogenization process for the alloy ingot is 450 ℃ for 24 h, the kinetic analysis results of the homogenization process are in good agreement with the experimental results.