论文标题
开发适合模拟FCC FE中错位迁移的原子间潜在
Development of interatomic potential appropriate for simulation of dislocation migration in fcc Fe
论文作者
论文摘要
脱位迁移的分子动力学（MD）模拟需要原子间相互作用的半经验潜力。尽管BCC FE有许多可靠的半经验潜力，但FCC的可用电位数量非常有限。在本研究中，我们测试了FCC FE的三个EAM电位（ABCH97 [Phil。A，75，713-732（1997）]，BCT13 [MSMSE 21，085004（2013）]和ZFS18 [J. Comp。Comp。Chem。39，2420-2420-2420-2431（2018）]）。发现ABCH97电位不能规定在任何温度下FCC相是最稳定的。另一方面，对于BCT13，ZFS18电位，FCC相总是比BCC相比BCC相更稳定。 HCP相是在任何温度下BCT13电位的最稳定相。为了解决这些问题，我们开发了两个新的EAM电位（MB1和MB2）。对于MB1电位而言，FCC相比BCC相位更稳定，但是MB2电位规定，BCC相是从FCC上部FCC-BCC转换温度T_GAMMA-DELTA到熔融温度，TM和FCC相的最稳定相。这种潜力还导致与FCC弹性常数的实验数据和合理的堆叠断层能达成了极好的一致性，这使其成为在本研究中考虑的所有半经验潜能中FCC FE中模拟脱位迁移的最佳潜力。 MD模拟表明，仅ZFS18，MB1和MB2电位实际上适合于FCC Fe中的脱位迁移的模拟。它们导致脱位速度的数量级相同，所有这些都表明，边缘位错比螺钉位错更快。但是，位错速度的实际值确实取决于使用的半经验潜能。
Molecular dynamics (MD) simulation of dislocation migration requires semi-empirical potentials of the interatomic interaction. While there are many reliable semi-empirical potentials for the bcc Fe, the number of the available potentials for the fcc is very limited. In the present study we tested three EAM potentials for the fcc Fe (ABCH97 [Phil. Mag. A, 75, 713-732 (1997)], BCT13 [MSMSE 21, 085004 (2013)] and ZFS18 [J. Comp. Chem. 39, 2420-2431 (2018)]) from literature. It was found that the ABCH97 potential does not provide that the fcc phase is the most stable at any temperature. On the other hand, the fcc phase is always more stable than the bcc phase for the BCT13, ZFS18 potentials. The hcp phase is the most stable phase for the BCT13 potential at any temperature. In order to fix these problems we developed two new EAM potentials (MB1 and MB2). The fcc phase is still more stable than the bcc phase for the MB1 potential but the MB2 potential provides that the bcc phase is the most stable phase from the upper fcc-bcc transformation temperature, T_gamma-delta, to the melting temperature, Tm, and the fcc phase is the most stable phase below T_gamma-delta. This potential also leads to an excellent agreement with the experimental data on the fcc elastic constants and reasonable stacking fault energy which makes it the best potential for the simulation of the dislocation migration in the fcc Fe among all semi-empirical potentials considered in the present study. The MD simulation demonstrated that only the ZFS18, MB1 and MB2 potentials are actually suitable for the simulation of the dislocation migration in the fcc Fe. They lead to the same orders of magnitude for the dislocation velocities and all of them show that the edge dislocation is faster than the screw dislocation. However, the actual values of the dislocation velocities do depend on the employed semi-empirical potential.
