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利用金相显微镜、差示扫描量热仪,扫描电镜研究了2055铝锂合金的均匀化处理工艺。结果表明:该合金适宜的均匀化处理制度为470℃/8 h+530~535℃/22~24 h。铸态合金树枝晶结构明显,由于Cu元素在晶界的大量偏析,形成了含少量Mg、Zn、Ag、Fe、Mn元素的Al Cu相和Al_2Cu相的共晶相以及AlCuFeMn第二相粒子。铸态合金的过烧温度为522.7℃。一级均匀化过程中,主要是含Cu、Zn、Mg、Ag等元素的低熔点共晶相先行溶解;二级均匀化时主要是Al_2Cu相回溶至基体,残余第二相的粒长在15μm左右,主要是含Cu、Fe和Mn元素的难溶相。第二级均匀化制度与均匀化动力学曲线匹配较好。
The homogenization process of 2055 Al-Li alloy was studied by metallographic microscope, differential scanning calorimeter and scanning electron microscope. The results show that the suitable homogenization treatment is 470 ℃ / 8 h + 530 ~ 535 ℃ / 22 ~ 24 h. The as-cast dendritic structure of the as-cast alloy is obvious. The eutectic phases of Al Cu phase and Al 2 Cu phase containing a small amount of Mg, Zn, Ag, Fe, Mn and the second phase particles of AlCuFeMn are formed due to the large segregation of Cu element at grain boundaries. The over-burning temperature of as-cast alloy is 522.7 ℃. In the first stage of homogenization, the low-melting eutectic phase containing Cu, Zn, Mg, Ag and other elements is dissolved in advance. When the second-level homogenization is performed, the Al 2 Cu phase is dissolved back into the matrix and the residual second phase 15μm, mainly containing Cu, Fe and Mn elements insoluble phase. The second-level homogenization system is better matched to the homogenization kinetic curve.