高氮奥氏体不锈钢中N与Cr、Mn、Mo键合性质研究

采用基于密度泛函理论的第一性原理计算方法对高氮奥氏体不锈钢中N与Cr、Mn、Mo键合性质进行研究。建立Fe-N-Cr、Fe-N-Mn及Fe-N-Mo晶胞,并对其电子结构进行计算,通过计算其晶胞总能量、体积変化率、电子态密度、重叠聚居数和电荷密度等电子结构参数,分析高氮奥氏体不锈钢中N与合金元素Cr、Mn、Mo的键合性质。结果表明:Cr、Mn、Mo取代顶角位置Fe原子时结构最稳定;N与Cr、Mn、Mo原子间存在离子键,成键轨道主要是N 2p与Cr、Mn、Mo的3d轨道;Fe、N与Cr、Mn、Mo原子存在交互排斥作用,形成反键。

Theoretical Study on Bonding Characteristics of Cr, Mn, Mo and N in High Nitrogen Austenitic Stainless Steel

The bonding characteristics of N with Cr, Mn, Mo in the high nitrogen austenitic stainless steels were studied by the first principles based on density functional theory. The electronic structures of Fe-N-Cr,Fe-N-Mn and Fe-N-Mo unit cell were calculated. The bonding characteristics of N with Cr, Mn, Mo in the high nitrogen austenitic stainless steels were analyzed by calculation of the electronic structure parameters, such as energy, charge density, overlap population and density of states. The results showed that the structure was more stable when the vertex positions of the Fe atom in the unit cell structure was replaced by the Cr, Mn, Mo atoms. There existed electrovalent bonds between N atom and Cr, Mn, Mo atoms, and bond orbitals were mainly composed of 3d orbital of Cr, Mn, Mo atoms. There was a mutual exclusion effect among Fe, N and Cr, Mn, Mo atoms, which led to the formation of an anti-bonding.