分子动力学
结晶学
变形(气象学)
雷亚克夫
动力学(音乐)
压力(语言学)
化学物理
原子间势
氢
Crystal(编程语言)
嵌入原子模型
应变率
分子物理学
作者
Ye Jiao,WenJiao Dan,Weigang Zhang
标识
DOI:10.1016/j.jallcom.2021.159330
摘要
Abstract In the present work, the deformation mechanisms of face-centred cubic (fcc) Fe–C single crystal with nanovoid containing hydrogen at various contents are investigated by molecular dynamics (MD) tensile simulations. The microstructural evolution of the supercell without H reveals that the plastic deformation mechanism is fcc→bcc→hcp continuous martensitic transformation. For the supercell containing 2 at% H, the mechanical response and plastic deformation mechanism are similar to those of the supercell without H. The difference is that bcc martensite nucleation is accompanied by dislocation nucleation, which indicates that a small amount of H addition will promote dislocation slip. When the H content reaches 5 at%, the dislocation slip enhanced by H completely overcomes the martensitic transformation and becomes the main plastic deformation mechanism. By analysing the per-atom potential energy of H atoms and Fe atoms, it is found that the potential energy of H atoms near the dislocation line and on the slip plane will increase, which may reduce the lattice resistance of dislocation slip. Moreover, the addition of H increases the average potential energy of fcc Fe atoms, which results in the reduction in Fe atomic binding, thus increasing the dislocation mobility. The dislocation slip causes localized plasticity on the nanovoid surface, which promotes the expansion of the nanovoid and leads to hydrogen embrittlement. The martensitic transformation and dislocation slip are prone to nucleation at the edge of the nanovoid, which indicates that in practical situations, void defects with sharp corners could induce premature plastic deformation in fcc crystals.
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