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近期文章
Mechanical properties of Fe-rich Si alloy from Hamiltonian (用哈密尔顿计算揭示富Fe硅合金的力学性能)
发布时间:2017-03-17

Mechanical properties of Fe-rich Si alloy from Hamiltonian 用哈密尔顿计算揭示富Fe硅合金的力学性能 
Tetsuo Mohri, Ying Chen, Masanori Kohyama, Shigenobu Ogata, Arkapol Saengdeejing, Somesh Kumar Bhattacharya, Masato Wakeda, Shuhei Shinzato & Hajime Kimizuka
npj Computational Materials 3, Article number: 10 (2017)
doi:10.1038/s41524-017-0012-4
Published online:10 March 2017
Abstract| Full Text | PDF OPEN

摘要:本文结合电子结构计算和统计力学手段(如团族变分方法、分子动力学模拟等),对富Fe硅合金力学性能的内在物理机制问题作了研究,其中团族变分方法、分子动力学模拟用来计算均相和多相系统。首先在均相系统中运用电子结构计算来研究弹性性能,并将Si含量增加时延展性损失的内在物理机制,归因于磁体积和D03排序的组合效应。本文以形成微结构的多相性作为典型实例,重点关注了晶界,并通过高精度电子结构计算研究了Si原子的偏析行为。找到了两种分离位点,即松散位点和紧密位点,发现二者的分离机制因场所而异。最后,本文主要通过电子结构计算,结合分子动力学模拟,对Fe-Si合金中的位错行为进行了研究。以处于螺旋位错线上的扭结成核和迁移的两种能垒,对固溶硬化和软化作了解释。此外,基于动力学蒙特卡罗模拟(KMC),本文还关注了扭结成核触发的滑移面优先选择,讨论了特定加工硬化行为的线索。 

Abstract: The physical origins of the mechanical properties of Fe-rich Si alloys are investigated by combining electronic structure calculations with statistical mechanics means such as the cluster variation method, molecular dynamics simulation, etc, applied to homogeneous and heterogeneous systems. Firstly, we examined the elastic properties based on electronic structure calculations in a homogeneous system and attributed the physical origin of the loss of ductility with increasing Si content to the combined effects of magneto-volume and D03 ordering. As a typical example of a heterogeneity forming a microstructure, we focus on grain boundaries, and segregation behavior of Si atoms is studied through high-precision electronic structure calculations. Two kinds of segregation sites are identified: looser and tighter sites. Depending on the site, different segregation mechanisms are revealed. Finally, the dislocation behavior in the Fe–Si alloy is investigated mainly by molecular dynamics simulations combined with electronic structure calculations. The solid-solution hardening and softening are interpreted in terms of two kinds of energy barriers for kink nucleation and migration on a screw dislocation line. Furthermore, the clue to the peculiar work hardening behavior is discussed based on kinetic Monte Carlo simulations by focusing on the preferential selection of slip planes triggered by kink nucleation. 

 
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