Cu-Cr合金低温时效析出过程的密度泛函理论

Density functional theory of Cu-Cr alloy during aging precipitation process at low temperature

采用雾化法制备过饱和Cu-Cr固溶体,利用透射电镜观察过饱和Cu-Cr固溶体低温时效富Cr区的显微形貌,利用能谱仪分析富集区Cr元素的含量,计算形成不同Cr含量富集区的形成能及合金熵,采用第一原理解释时效析出过程中合金富集区的电子结构变化。结果表明:随时效时间的增加,Cr不断在基体中富集,时效析出是一个扩散迁移过程;富集区是一种亚稳态,有逐渐向稳定态转变的趋势,即Cr析出是固溶体能量降低的一种方式。态密度的计算证实,Cr含量56.0%时富集区发生结构转变(出现GP区),体系内原子化学环境发生变化。

Supersaturated Cu-Cr solid solution was prepared by atomization. The microstructures of Cr rich zone in Cu-Cr solid solution were investigated by transmission electron microscopy and electron energy disperse spectroscopy. The formation energy and entropy of different Cr soluble enrichment districts were calculated. The electric structure changes of richment zones during aging precipitation process were explained by the first principle. The mechanism of aging precipitation was explained. The results show that the GP zone is presented at relatively low temperature, the concentration of Cr also increases due to the soluble enrichment process. The soluble enrichment is a metastable phase and declines the system energy. The structure of enrichment zones with 56%Cr is transformed and the environment of atoms in GP zone is charged too.