摘要
为了从原子层面上了解钢中铌元素对奥氏体转变的作用,采用基于密度泛函理论(DFT)的第一性原理方法,计算了在奥氏体和铁素体中铌原子或碳原子分别占据间隙位置或者置换位置几种构型的体系总能量和结合能,由此判断铌及碳的固溶形式。结果表明,在奥氏体中,铌原子只能以置换固溶形式存在,碳原子可以以间隙固溶或者置换固溶的形式存在;在铁素体中,铌原子和碳原子均不能够固溶。进一步计算了在奥氏体中碳原子的迁移扩散能量,考察铌原子的存在对碳原子迁移的影响。在奥氏体中,以置换固溶形式存在的铌原子可导致碳原子的迁移激活能提高和系统能量出现较大波动,正是铌的这个效应使奥氏体向铁素体的转变温度降低,并且造成铁素体晶粒细化。
Abstract：In order to reveal the influence of niobium in steel on the austenite transformation, the first-principle calculations based on density functional theory were carried out. First, the total energies and binding energies of some configurations for a niobium atom or a carbon atom in austenite or ferrite were calculated to determine their solid solution. The calculation results indicate that in austenite, niobium exists in the form of substitution solid solution and carbon could be in the form of substitution solid solution or interstitial solid solution. But in ferrite, neither niobium nor carbon exists in the form of solid solution. Then, the diffusion energies of a carbon atom in austenite was calculated to investigate the influence of niobium on the diffusion behavior of carbon. The results show that the system total energy rises and falls heavily and the diffusion activation energy increases when a carbon atom diffuses near by the niobium atom which exists as a substitution solid solution in austenite. It is this effect of niobium which lead to the decrease of transformation temperature from austenite into ferrite and the grain refinement of ferrite.
出处
《热加工工艺》
CSCD
北大核心
2014年第2期28-31,共4页
Hot Working Technology
基金
国家自然科学基金资助项目(50845065)
内蒙古自治区自然科学基金资助项目(2010Zd21)
关键词
铌微合金钢
第一性原理
固溶形式
迁移行为
niobium micro-alloyed steel
first principle method
solid solution
diffusion behavior
作者简介
刘学杰（1953-），男，广东人，教授，博士；E-mail：xuejieliu2000@yahoo．com
