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实现Fe/Al界面结合是保证钢/铝异种金属激光焊接质量的关键。采用基于密度泛函理论的第一性原理方法,通过构造Fe/Al界面模型,计算了体系的能量与电子结构,讨论了Co、V、Zn、Sn等元素微合金化在Fe/Al界面处的作用。结果表明:Co、V优先置换界面处的Fe原子,而Zn、Sn优先置换的却是Al原子,Fe/Al界面结合主要是Fe-sd与Al-sp轨道之间杂化以及Fe-Al发生的离子键作用。微合金化使Fe/Al界面的断裂功增加,其增强由大到小的顺序为:Co、V、Zn、Sn。电子态密度、电子占据数以及电子密度的计算结果表明:利于Fe/Al界面结合的主要原因是微合金化导致跨界面Fe-Al之间的成键作用增强。对Co而言,主要是Fe-sd、Al-sp、Co-sd之间存在较强共价键和离子键的复合作用;对V而言,主要是V-dp、Fe-d和Al-p之间的轨道杂化作用;而对Zn和Sn而言,则主要是Fe-Al之间发生的离子键作用。
Achieving Fe / Al interface bonding is the key to ensure the quality of dissimilar metal laser welding of steel / aluminum. Based on the first principles method based on density functional theory, the energy and electron structure of the system were calculated by constructing the Fe / Al interface model. The effects of Co, V, Zn and Sn microalloying on Fe / Al interface Role. The results show that Co and V preferentially displace Fe atoms in the interface, while Zn and Sn preferentially displace Al atoms, and the Fe / Al interface is mainly composed of Fe-sd and Al-sp orbital and Fe-Al Ion key role. Micro-alloying increases the fracture work at the Fe / Al interface, and the order of enhancement is from small to large: Co, V, Zn, Sn. The calculated results of electron density, electron occupancy and electron density show that the main reason for the favorable bonding of Fe / Al interface is that the microalloying leads to the enhancement of the bonding between Fe-Al. For Co, it is mainly the complex interaction of Fe-sd, Al-sp and Co-sd with strong covalent bonds and ionic bonds; for V, the main ones are V-dp, Fe-d and Al- p orbital hybridization; while for Zn and Sn, it is mainly the ionic bond that occurs between Fe-Al.