2055铝锂合金双级均匀化工艺

Two-stage Homogenization Process of 2055 Al-Li Alloys

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＋530535℃/2224 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Al2Cu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Al2Cu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 two-stage homogenization process of 2055 Al-Li alloy was investigated by OM, DSC and SEM. The results show that the proper two-stage homogenization process of 2055 Al-Li alloy is 470 °C/8 h＋530535 °C/2224 h. The dendritic structure of as-cast alloys is obvious, the intermetallic phases in as-cast alloy consist of Cu, Ag, Mg, Zn, Fe and Mn enriched eutectic aluminides, Cu enriched eutectic aluminides Al2Cu and AlCuFeMn second phase. The overburnt temperature of the alloy is 522.7 °C. During the first homogenization process, Cu, Mg, Zn and Ag enriched eutectic aluminides dissolve into the matrix firstly, and then Cu enriched non-equilibrium aluminides Al2Cu gradually dissolve into the matrix except a small amount of Al-Cu-Fe-Mn phases, and the size of residual phases is about 15 μm. The second homogenization process agrees well with the homogenization kinetic analyses.