Local lattice instability at a dislocation nucleation and motion
Local lattice instability at a dislocation nucleation and motion
复制标题
位错成核和运动时的局部晶格不稳定性
DOI：
10.1051/jp4:2001501
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Y. Tomita
中科院分区：
文献类型：
--
作者：
K. Yashiro;Y. Tomita
用分子动力学方法研究了镍单晶纳米试样在[001]拉伸下部分位错的形核和运动的动力学过程，从均匀变形体中局域晶格的两个连续失稳行为的角度，对机制和机理进行了新的讨论;第一个失稳行为是局部晶格的坍塌，破坏了均匀泊松收缩，导致变形集中。二是形变集中区滑移面上晶格的不稳定剪切，位错的形核和滑移表现为原子在滑移面上的迁移。基于弹性刚度系数B ijkl来评估不稳定行为开始的标准，即Wang等人提出的不稳定标准[Wang，J.等人，物理修订信函71-25（1993）。4182 - 4185]对局部不稳定性进行了评价。结果表明，第一和第二失稳行为的弹性刚度在每次开始时都变为负值。因此，局部晶格不稳定性导致位错形核和运动，并且可以通过局部B ijkl的负性来定量评估。
By means of molecular dynamics technique, the dynamic process of nucleation and motion of a partial dislocation is carefully investigated in a nanoscopic specimen of single crystalline nickel under [001] tension, The mechanism and mechanics are discussed in a new light of the two successive unstable behaviors of local lattices observed in the homogeneously deformed body; the first unstable behavior is the collapse of local lattices that breaks the homogeneous Poisson's contraction, leading to the deformation concentration. The second is the unstable shear of lattices on a slip plane in the deformation concentrated region The nucleation and glide of dislocation can be observed as the migration of atoms on the slip plane as a result of these unstable behaviors. The criteria of the onset of the unstable behaviors are evaluated based on the elastic stiffness coefficients, B ijkl , That is, the instability criteria proposed by Wang et al [Wang, J. et al., Phys. Rev. Lett. 71-25 (1993). 4182 4185] are adopted to evaluate local instability. The results show that the elastic stiffness of the first and second unstable behaviors becomes negative at each onset. Thus, the local lattice instabilities cause the dislocation nucleation and motion and can be quantitatively evaluated by the negativeness of local B ijkl .