Ab initio characterization of B, C, N, and O in bcc iron: Solution and migration energies and elastic strain fields
Ab initio characterization of B, C, N, and O in bcc iron: Solution and migration energies and elastic strain fields
复制标题
DOI：
10.1016/j.commatsci.2016.07.037
复制
发表时间：
2016-11
影响因子：
3.3
通讯作者：
M. Souissi;Ying Chen;M. Sluiter;H. Numakura
中科院分区：
文献类型：
--
作者：
M. Souissi;Ying Chen;M. Sluiter;H. Numakura
通过系统的密度泛函理论计算，探索了从理论上确定体心立方铁中B、C、N、O等元素性质的实用可靠方法。用超晶胞方法计算了不同条件下溶质原子的溶解能、迁移能和弹性应变场。通过对周期超胞中溶质原子与其映象的伪弹性相互作用进行校正，在不使用非常大的超胞的情况下，得到了对溶液能量的合理估计。结果表明，修正对迁移能量并不重要，因为它对稳定位置和鞍点的能量进行了类似的修正。拉姆达张量唯一地描述了溶质原子诱导的应变场，已经对四种不同构型的物种进行了评估，首先是通过在零应变计算中获得的力偶极张量，其次是根据零应力计算中超晶胞尺寸的变化。这两个程序给出的结果相似，通常相差几个百分点。八面体间隙位碳和氮的计算值与实验值相当。当B和O的实验数据可用时，这些评估将解决这些原子物种在体心立方铁中的争议位置。
Practical and reliable methods for theoretically determining the properties of B, C, N, and O in bcc iron have been explored by systematic DFT calculations. The energies of solution and migration, and the elastic strain fields due to the solute atom have been evaluated by supercell calculations under various conditions. By applying correction for spurious elastic interaction of the solute atom with its images in the periodic supercells, reasonable estimates of the solution energy have been obtained without employing very large supercells. The correction turned out unimportant for the migration energy, as it modifies the energies of the stable position and the saddle-point similarly. The lambda tensor, which uniquely characterizes the strain field induced by a solute atom, has been evaluated for the four species of various configurations, first through the force-dipole tensor obtained in zero-strain calculations, and second from changes in supercell dimensions in zero-stress calculations. The two procedures give similar results that typically differ by a few per cent from each other. The computed values for C and N in octahedral interstitial sites are comparable to experimental values. When experimental data become available for B and O, these evaluations will resolve the as-yet contentious location of these atomic species in bcc iron.