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采用Thermo-Calc软件计算和光学显微镜、扫描电镜、能谱仪及示差扫描量热仪实验分析手段,研究了Al-Zn-Mg-Cu系富铝角等温(480℃)截面图和Al-12Zn-xMg-1.5Cu合金的垂直截面图。结果表明,相平衡计算结果与实验分析吻合良好。在等温等锌截面计算相图中,随着Zn含量提高,α(Al)单相区和α(Al)+S(Al2CuMg)相区分别缩小和扩大,在α(Al)单相区内,Mg在铝固溶体的固溶度降低,Cu的固溶度变化不大。在等温等铜截面计算相图中,随着Cu含量降低,α(Al)单相区扩大,α+S(Al2CuMg)两相区缩小。合金元素的极限固溶度对温度极为敏感,在多相共晶点附近温区,合金元素的极限固溶度最大。
The effects of Al-Zn-Mg-Cu on the isothermal (480 ℃) cross section of Al-12Zn alloy and the Al-12Zn -xMg-1.5Cu alloy vertical cross-section. The results show that the phase equilibrium calculation results agree well with the experimental results. In the isothermal calculation phase diagram of zinc cross section, the α (Al) single phase and α (Al) + S (Al2CuMg) phase regions decrease and expand respectively with the increase of Zn content. The solid solubility of Mg in the aluminum solid solution decreases, and the solid solubility of Cu does not change much. In isothermal calculation of phase diagram of copper cross section, the α (Al) single phase region expands and the α + S (Al2CuMg) two phase region shrinks with decreasing Cu content. The ultimate solid solubility of alloying elements is extremely sensitive to temperature, and the ultimate solid solubility of alloying elements is the highest in the vicinity of the polyphase eutectic point.