合金元素对Cu/γ-Fe界面特性影响的第一性原理研究

First-principles study of effects of alloying elements on Cu/γ-Fe interfacial properties

采用基于密度泛函理论的第一性原理方法,计算合金原子在Cu/γ-Fe界面不同点阵位置的置换能,确定合金元素在Cu/γ-Fe界面模型的占位。通过对晶格错配度、界面结合能、界面能和电子结构的计算分析合金元素对Cu/γ-Fe界面特性的影响。计算结果表明:合金元素B、Si、P、Al、Zr使界面结合能增大,增强Cu/γ-Fe界面稳定性;B、Si、P等11种合金元素则会使界面能降低,有利于γ-Fe的时效析出形核。因此,B、Si、P、Al、Zr可以促进γ-Fe的析出,同时形成稳定的γ-Fe相。通过合金原子相对体积、晶格错配度和差分电荷密度的计算,分析合金元素的作用机制。

The substitutional energies of alloying atoms at different interface sites were calculated by first-principles method based on density functional theory, which gives the most favorable sites of alloying atoms. The lattice misfits, work of adhesion, interfacial energy and electronic structure were calculated to analyze the effects of alloying elements on Cu/γ-Fe interfacial properties. The results show that alloying elements B, Si, P, Al, Zr can improve the stability of Cu/γ-Fe interface by increasing the work of adhesion, while eleven kinds of alloying elements such as B, Si, P etc. reduce the interfacial energy, which is beneficial to the nucleation of γ-Fe. Therefore, B, Si, P, Al, Zr may accelerate the precipitation and form stable γ-Fe phase. The solute volumes of alloying atoms, lattice misfits and charge density difference explain well on the working mechanisms of the alloying elements.