钒微合金钢中α-Fe/V₄C₃界面结构与稳定性的第一性原理计算

In order to investigate the interface stability of α-Fe/V₄C₃, the interface structure of three different atomic stacking sequences (Fe-on-C, Fe-on-V and Bridge) of (100)_α-Fe/(100)_V4C3 were optimized by using the first-principles calculations with pseudo potential plane wave method. The structural stability of α-Fe/V₄C₃ was measured by the work done of separation for the three configurations. The calculated interfacial separation work of the three configurations is 4.29, 1.43 eV and 2.70 eV, respectively, which larger interfacial separation work indicating stronger interface stability.Therefore, V₄C₃ precipitated in α-Fe mainly exists in the Fe-on-C configuration, and its interface stability is the strongest. The electronic structure properties of α-Fe/V₄C₃ were studied by calculating the density of states, differential charge density and electron localization function. The results show that in the Fe-on-C structure configurations, there is a charge-depleted zone for Fe atoms at the interface, and the lost charge transfer to the interface. Due to the strong electronegativity of C atoms, strong mixed ions/covalent bonds are formed at the interface, and the bond and interaction between Fe and C atoms are significantly stronger than that between Fe atoms and V atoms. Meanwhile, according to the total density of states and projected density of states, it is found that the Fe-d orbital and the C-p orbital hybridize in the -4.5 eV to -2.5 eV region, promoting the formation of the Fe-C covalent bond.