La、Al在Fe晶界上协同作用的第一性原理研究

First principles study on the synergistic effect of La and Al on Fe grain boundary

采用基于密度泛函理论的第一性原理,研究了稀土La和Al在bcc-Fe中Fe晶界处的协同作用影响.计算了La和Al在晶界、表面、晶内的形成能,建立La、Al共存于晶界模型,通过电荷密度、布居分布手段分析了La、Al原子对晶界的影响.结果表明:La、Al原子易偏聚在晶界处,且La-Al的原子间距与体系结合能成正比关系. La的掺杂改善了晶界处的电荷分布情况,促进了Al原子与周围Fe原子间的相互作用,态密度曲线的计算结果显示,La原子的加入能够使La、Fe及Al原子间的键的结合力更强,从而提高了界面结合强度.

Based on the first principles of density functional theory, the synergistic effect of La and Al on the Fe grain boundary in bcc-Fe was studied. The formation energies of La and Al at grain boundary, surface and intragranular were calculated. On this basis, the model of coexistence of La and Al in grain boundary is established, the influence of La and Al atoms on grain boundary is analyzed by means of charge density and population distribution. The results show that La and Al atoms tend to segregate at the grain boundary, and the atomic spacing of La Al is proportional to the binding energy of the system. In addition, the doping of La improves the charge distribution at the grain boundary and promotes the interaction between Al and Fe atoms. The calculated results of the density of states curve show that the addition of La can make the bond strength among La, Fe and Al atoms stronger, thus improving the interface bonding strength.