Acta Metall Sin  2020, Vol. 56 Issue (9): 1286-1294    DOI: 10.11900/0412.1961.2020.00021
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Interaction Between Interstitial Dislocation Loop and Micro-Crack in bcc Iron Investigated by Molecular Dynamics Method
LIANG Jinjie1,2, GAO Ning2,3, LI Yuhong1()
1 School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
3 Key Laboratory of Particle Physics and Particle Irradiation, Ministry of Education, Institute of Frontier and Interdisciplinary Science，Shandong University, Qingdao, Qingdao 266237, China
Abstract

 ZTFLH: O469
Fund: National Magnetic Confinement Fusion Energy Research and Development Program of China(2018YFE0308101);National Natural Science Foundation of China(11675230);National Natural Science Foundation of China(11775102);Youth Innovation Promotion Association, Chinese Academy of Sciences(2016366)
Corresponding Authors:  LI Yuhong     E-mail:  liyuhong@lzu.edu.cn
 Fig.1  Schematics of interaction between the interstitial dislocation loop and micro-crack (l—distance between dislocation loop and crack tip in Y direction, R—radius of dislocation loop, d—distance between dislocation loop and crack tip in X direction, P—the position of the crack tip, k—slope of crack, 2θ—crack tip opening angle)(a) crack is inside of the material(b) crack is from the free surface of material Fig.2  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=1.5 nm, k=0.05 and R=1.5 nm Fig.3  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=3.2 nm, k=0.05 and R=1.5 nm Fig.4  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=4.5 nm, k=0.05 and R=1.5 nm(a) formation of 1/2[$111ˉ$] dislocation segment after the conjugate gradient method relaxation (b~e) molecular dynamics simulation results at 300 K under 0 Pa pressure with time up to 1.8×10-11 s, 3×10-11 s, 3.09×10-11 and 3.12×10-11 s, respectively (The movements of dislocation loop and 1/2[$111ˉ$] dislocation segment along their Burgers vectors are shown in Figs.4b and c, respectively. The interactions between them are shown in Figs.4d and e) Fig.5  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=1.5 nm, R=1.5 nm and k=0.10 Fig.6  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=1.5 nm, R=1.5 nm and k=0.15 Fig.7  Evolutions of the system with the interaction between the dislocation loop and micro-crack with d=1.5 nm, R=1.5 nm and k≥0.20 Fig.8  Evolutions of dislocation loop and micro-crack with the repulsive interaction between them with d=3.2 nm, R=1.5 nm and k=0.10 (The distance between them increases with simulation time (t))(a) t=1.5×10-12 s(b) t=4.8×10-12 s(c) t=7.5×10-11 s Table 1  The simulation time for dislocation loop to be fully absorbed by micro-crack with and without the effect of free surface with d=15 nm under the condition of different R and k(10-3 ns)