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采用差热分析仪(DSC)、光学显微镜(OM)、扫描电镜(SEM)、透射电镜观察(TEM)、布氏硬度测试等方法研究了一种新型Al-6Zn-2.5Mg-0.6Cu(mass%)合金在单、双级均匀化过程的组织性能演变。结果表明:Al-6Zn-2.5Mg-0.6Cu(mass%)合金铸锭组织中存在着严重的枝晶偏析,由ɑ(Al)和T(Al-Mg-Zn-Cu)四元相组成的非平衡共晶相沿晶界呈连续链状分布;合金经470℃×24 h均匀化处理过后,铸锭晶界得到了明显的净化,晶界上原本大量存在的非平衡共晶相回溶入基体中;铸锭先在250℃×4C h下进行均匀化预处理有利于获得尺寸细小、均匀分布的含Mn、Cr析出相,提高合金的布氏硬度值,确定该新型合金铸锭的最优均匀化工艺为250℃×4 h+470℃×24 h。
A new type of Al-6Zn-2.5Mg-0.6Cu (mass ratio) was studied by differential scanning calorimetry (DSC), optical microscope (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brinell hardness test. %) Alloy in the single, two-stage homogenization process of organizational performance evolution. The results show that there are serious dendritic segregations in Al-6Zn-2.5Mg-0.6Cu (mass%) alloy ingot, composed of Al and T (Al-Mg-Zn-Cu) Unbalanced eutectic phase along the grain boundary was continuous chain distribution; alloy by 470 ℃ × 24 h after homogenization, the ingot grain boundaries have been significantly purified, the grain boundary existing a large number of non-equilibrium eutectic phase dissolved back In the matrix, the homogenization of the ingot before 250 ℃ × 4C h is beneficial to obtain the small and uniform distribution of Mn and Cr precipitates, and increase the Brinell hardness of the alloy to determine the best The optimal homogenization process is 250 ℃ × 4 h + 470 ℃ × 24 h.