采用第一原理赝势平面波方法计算了Al-Sc合金固溶体、有序相和无序相结构对应的形成焓.在无序合金的电子结构研究中,引入了可以描述无序合金结构环境的小尺寸超单胞模型——SQS模型.计算结果表明:超饱和固溶体中的Sc原子具有偏聚产生L1_2结构的Al_3Sc析出相和L1_0结构的AlSc析出相的趋势.依据对各相的电子结构及电子密度分析结果,初步探讨了时效处理导致超饱和固溶体Al(Sc)中偏聚产生L1_2结构Al_3Sc析出相的形成机理. The formation enthalpies of solid solution, ordered phase and disordered phase structure of Al-Sc alloy were calculated by the first-principle pseudopotential plane wave method. In the electronic structure study of disordered alloys, we introduced the small Dimensional supermass cell model.SQS model.The calculated results show that the Sc atom in supersaturated solid solution tends to segregate to produce the Al 3 Sc precipitation phase of L1 2 structure and the AlSc precipitation phase of L1 0 structure.Based on the analysis of the electronic structure of each phase and the electron Density analysis, the forming mechanism of Al_3Sc precipitated phase of L1_2 structure caused by the segregation of Al (Sc) in supersaturated solid solution was preliminarily discussed.