摘要:
基于密度泛函理论第一性原理方法,采用广义梯度近似下的PW91泛函形式,计算了合金元素Cr, Mo, Ni固溶于γ-Fe(C)的电子结构,从重叠聚居数、电荷布居数、态密度、差分电荷密度及结合能等计算结果分析探讨了合金元素在γ-Fe(C)中的键合性质及对奥氏体相稳定性的影响。结果表明： Cr, Mo在奥氏体晶胞中都存在金属键、共价键和微弱的离子键的共同作用,而Ni仅有金属键和共价键作用,几乎不受离子键作用,成键轨道主要是Cr, Mo, Ni的d 轨道与Fe 3d, C 2p轨道的交互作用形成的。依据合金元素对γ-Fe(C)电子结构的影响,探讨了Cr, Mo, Ni固溶后对奥氏体相稳定性的影响。
Abstract:
Based on density functional theory and using the first-principle method, the electronic structures of γ-Fe(C) with Cr, Mo, and Ni are calculated within the generalized gradient approximation (GGA)-PW91. Meanwhile, the effects of alloys on the bonding characters and austenitic stability are studied by the overlap population, mulliken charge population, density of states, charge density difference, and cohesive energy. The results show that there coexist the metallic bond, covalent bond and weak ionic bond in each of γ-Fe(C)-Cr and γ-Fe(C)-Mo unit cell, while only metallic bond and covalent bond coexist inγ-Fe(C)-Ni. The bonding orbit is mainly determined by the interactions between the d orbits of alloy atoms and the orbits of Fe 3d and C 2p. Moreover, the effects of Cr, Mo, Ni solution on austenitic stability are investigated by studying the influence of alloy element onγ-Fe(C) electronic structure.
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