Studying dislocation-induced shielding effect on the crack-tip in polycrystal by discrete dislocation dynamics
Studying dislocation-induced shielding effect on the crack-tip in polycrystal by discrete dislocation dynamics
复制标题
通过离散位错动力学研究位错引起的多晶裂纹尖端屏蔽效应
DOI：
10.1016/j.ijsolstr.2018.08.012
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发表时间：
2019
影响因子：
3.6
通讯作者：
Li Zhenhuan
中科院分区：
文献类型：
--
作者：
Liang Shuang;Zhu Yaxin;Huang Minsheng;Li Zhenhuan
位错对裂纹尖端的屏蔽效应不仅与位错的数量有关，而且与位错距裂纹尖端的距离有关。前者与位错的形核密切相关，而后者与晶粒尺寸和晶界对位错的阻碍作用密切相关。本文进一步发展了离散位错动力学框架，特别引入了裂尖位错发射方案，并对多晶体中位错对裂尖的屏蔽效应进行了一系列离散位错动力学模拟。研究了Frank-Read源的位错形核（DNFR）和裂纹尖端的位错发射（DECT）在屏蔽效应中的不同作用，表明DECT机制比DNFR机制更重要。位错的屏蔽效应受晶粒尺寸和位错穿过晶界的能垒的影响。随着晶粒尺寸的增大，位错对裂纹尖端的屏蔽作用显著增强，表现出较强的晶粒尺寸效应。此外，随着GB能垒的增加，位错对裂纹尖端的屏蔽作用先增大后达到峰值，最后减小，呈现出有趣的“山”形关系.随着晶粒尺寸的增大，这种山形相关性逐渐变平。这些有趣的结果丰富了我们对多晶体中位错诱导裂纹尖端屏蔽效应的理解。
The dislocation-induced shielding effect on the crack-tip depends on not only the number of dislocations but also the distance of dislocations from the crack-tip. The former is closely related to the nucleation of dislocation but the latter to the grain size and the obstruction of grain boundaries (GBs) to dislocations. In this paper, a discrete dislocation dynamic framework was further developed with a crack-tip dislocation emission scheme especially introduced, and then a series of discrete dislocation dynamic simulations were performed to study the shielding effect of dislocations on the crack-tip in poly-crystals. The different roles of the dislocation nucleation from the Frank-Read sources (DNFR) and dislocation emission from the crack-tip (DECT) in the shielding effect were studied, which indicates the DECT mechanism plays more important role compared with the DNFR one for the cases considered here. The shielding effect of dislocation is dominated by the grain size as well as the energy barrier for dislocation transmission across GB. With the increase of grain size, the shielding effect of dislocations on the crack-tip increases significantly, showing strong grain size effect. Moreover, with the increase of the GB energy barrier for dislocation transmission, the shielding effect of dislocations on the crack-tip first increases and then reaches its peak and finally decreases, showing an interesting mountain-shaped dependence on the GB energy barrier. This mountain-shaped dependence is gradually flattened with the increases of grain size. These interesting results enrich our understanding of the dislocations-induced shielding effect on the crack-tip in the poly-crystals.
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影响因子：
2.2
作者：
Chuantao Hou;Zhenhua Li;Minsheng Huang;Chaojun Ouyang
通讯作者：
Chuantao Hou;Zhenhua Li;Minsheng Huang;Chaojun Ouyang
影响因子：
5.3
作者：
T. Bhandakkar;Audrey C. Chng;W. Curtin;Huajian Gao
通讯作者：
T. Bhandakkar;Audrey C. Chng;W. Curtin;Huajian Gao
影响因子：
5.3
作者：
L. Fischer;G. Beltz
通讯作者：
L. Fischer;G. Beltz
影响因子：
9.8
作者：
Minsheng Huang;J. Tong;Zhenhua Li
通讯作者：
Minsheng Huang;J. Tong;Zhenhua Li
DOI：
10.1007/bf02661312
发表时间：
1972-01-01
期刊：
METALLURGICAL TRANSACTIONS
影响因子：
--
作者：
HIRTH, JP
通讯作者：
HIRTH, JP