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Atomic simulation for influence of helium atom on movement of edge dislocation in nickel

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Transactions of Nonferrous Metals Society of China 2015年第8期25卷 2666-2674页

作者：阳喜元岭南师范学院物理科学与技术学院湛江524048

The molecular dynamics （MD） simulation and the modified analytical embedded-atom method （MAEAM） were used to study the influence of a He atom on the movement of the（a/2）？110？{111} edge dislocation in Ni. First, the calculated Burgers vector distribution shows that the equilibrium dissociation distance （Ded） and the stacking fault energy （Esf） between two partial edge dislocations are about 25.95 ？ and 108 mJ/m2, respectively. Then, the obtained formation energies （Ef） of a He atom at some different sites demonstrate that the He atom is attracted and repelled in the tension and compression regions, respectively. And the He？dislocation interaction reveals that an interstitial He atom plays a more significant role in the dislocation movement than a substitutional He atom. Finally, it is found that the movement of an interstitial He atom is apparent as the first partial dislocation bypasses and the edge dislocation offers fast-diffusion path for the migration of a He atom.

关键词： movement edge dislocation He atomic simulation Ni

Relaxed energy and structure of edge dislocation in iron

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Chinese Physics B 2011年第2期20卷 363-369页

作者：张研解丽娟张建民徐可为 College of Physics and Information Technology Shaanxi Normal University Laboratoire SPMS ' Ecole Centrale ParisCNRS-UMR 858092295 Cha tenay-Malabry CedexFrance State Key Laboratory for Mechanical Behaviour of Materials Xi'an Jiaotong University

With modified analytical embedded-atom method and molecular dynamics simulation, this paper simulates the strain energy and the equilibrium core structure of a（100） edge dislocation in BCC metal iron on atomistic scale. In addition, the trapping effect of dislocation on vacancy is investigated as well. The results show that the equilibrium dislocation core is quite narrow and has a C2v symmetry structure. Calculated strain energy Es of the dislocation is a linear function of ln（R/2b） while R ≥ 5.16 A（1A = 0.1 nm）, in excellent agreement with the elasticity theory prediction. Determined core radius and energy are 5.16 A and 0.62 eV/A, respectively. The closer the vacancy to the dislocation line is, the lower the vacancy formation energy is, this fact implies that the dislocation has a trend to trap the vacancy, especially for a separation distance of the vacancy from dislocation line being less than two lattice constants.

关键词： iron edge dislocation vacancy modified analytical embedded-atom method

Elastic behaviour of an edge dislocation near a sharp crack emanating from a semi-elliptical blunt crack

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Chinese Physics B 2010年第1期19卷 409-416页

作者：方棋洪宋豪鹏刘又文 College of Mechanics and Aerospace Hunan University

The interaction between an edge dislocation and a crack emanating from a senti-elliptic hole is dealt with. Utilizing the complex variable method, closed form solutions are derived for complex potentials and stress fields. The stress intensity factor at the tip of the crack and the image force acting on the edge dislocation are also calculated. The influence of the morphology of the blunt crack and the position of the edge dislocation on the shielding effect to the crack and the image force is examined in detail. The results indicate that the shielding or anti-shielding effect to the stress intensity factor increases acutely when the dislocation approaches the tip of the crack. The effect of the morphology of the blunt crack on the stress intensity factor of the crack and the image force is very significant.

关键词： edge dislocation blunt crack shielding effect image force

On edge dislocation in a multilayered laminate

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Theoretical & Applied Mechanics Letters 2011年第2期1卷 25-28页

作者： Xu Wang~(a) School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237, China School of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China

We investigate the elastic field induced by an edge dislocation in a multilayered laminated composite composed of(N—2)thin bonded elastic layers sandwiched between two semi-infinite elastic media.A simple closed-form solution is obtained when all the phases have equal shear modulus but different Poisson's ratios,and when the dislocation is located in the upper semi-infinite *** image force acting on the dislocation due to its interaction with the multilayered structure is also derived. Several specific examples are discussed in detail to illustrate the mobility of the edge dislocation. Some interesting behaviors of the dislocation are *** results indicate that it is possible to find at most(N—2)equilibrium positions for the edge dislocation in an N-phase composite structure.

关键词： laminated composite edge dislocation image force equilibrium position

edge dislocation Emission from an Elliptically Blunted Crack Tip with Surface Effects

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Edge Dislocation Emission from an Elliptically Blunted Crack...

Molecular dynamics study of interactions between edge dislocation and irradiation-induced defects in Fe–10Ni–20Cr alloy

中国力学学会学术大会'2009

作者： Fang QH~*,Liu Y~*,Huang BY~*,Liu YW~+ * State Key Laboratory for Powder Metallurgy,Central South University,Changsha 410083,China, + College of Mechanics and Aerospace,Hunan University, Changsha 410082,China

The explicit expressions for critical stress intensity factors are derived for edge dislocation emission from an elliptically blunt crack with surface effects under modeⅠand modeⅡ*** influence of surface effects on ... 详细信息

关键词： edge dislocation blunt crack surface stress dislocation emission

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Chinese Physics B 2023年第2期32卷 80-86页

作者：熊涛文陈小平林也平贺新福杨文胡望宇高飞邓辉球 College of Materials Science and Engineering Hunan UniversityChangsha 410082China School of Physics and Electronics Hunan UniversityChangsha 410082China China Institute of Atomic Energy Beijing 102413China Department of Nuclear Engineering and Radiological Sciences University of MichiganAnn Arbor MI48109USA

Irradiation-induced defects frequently impede the slip of dislocations, resulting in a sharp decline in the performance of nuclear reactor structural materials, particularly core structural materials. In the present work, molecular dynamics method is used to investigate the interactions between edge dislocations and three typical irradiation-induced defects(void,Frank loop, and stacking fault tetrahedron) with the sizes of 3 nm, 5 nm, and 7 nm at different temperatures in Fe–10Ni–20Cr alloy. The critical resolved shear stresses(CRSSs) are compared among different defect types after interacting with edge dislocations. The results show that the CRSS decreases with temperature increasing and defect size decreasing for each defect type during the interaction with edge dislocations, except for the case of 3-nm Frank loops at 900 K. According to a comparison, the CRSS in Frank loop is significantly higher than that of others of the same size, which is due to the occurrence of unfaulting and formation of superjog or stacking-fault complex during the interaction. The atomic evolution of irradiation-induced defects after interacting with dislocations can provide a novel insight into the design of new structural materials.

关键词： molecular dynamics simulation edge dislocation irradiation-induced defects austenitic stainless steel

Electronic structure of edge dislocation of core-doped Ti in Fe

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Progress in Natural Science:Materials International 2004年第6期 15-20页

作者： DANG Hongli 1 *,WANG Chongyu 1,2,3 and SHU Xiaolin 1(1. Central Iron and Steel Research Institute,Beijing 100081,China 2. Department of Physics,Tsinghua University,Beijing 100084,China 3. International Center for Materials Physics,Academica,Shenyang 110016,China) Central Iron and Steel Research Institute，Beijing 100081，China Central Iron and Steel Research Institute，Beijing 100081，China Department of Physics，Tsinghua University，Beijing 100084 China International Center for Materials Physics，Academica，Shenyang 110016，China

The electronic structure of an edge dislocation doped Ti lying in the (001) plane with Burgers Vector along [100] direction in body-centered cubic iron is investigated using the first principles discrete variational method (DVM) based on the density-functional theory. The binding energy,impurity formation energy,interatomic energy,Mulliken orbital populations and charge density difference are presented in this paper. By calculating the binding energy of the clean dislocation system and the Ti-doped system,it is found that the binding energy of Ti-doped dislocation system is lower than that of the clean dislocation system,which implies that the Ti-doped dislocation system is more stable than the clean dislocation system. The calculated result of the impurity formation energy predicts the trapping effect of dislocation core for Ti,which shows that Ti atom prefers to occupy the place at the dislocation core. The calculated results of the interatomic energy and the difference charge density of dislocation doped Ti system indicate that the stronger bonding formed between the Ti impurity and its neighbor Fe atoms will affect the mechanical property of edge dislocation. Considering the influence of Ti on the electronic structure and the energies,we can predict that the trace Ti in transition metal Fe with dislocation defect can give a significant contribution to the solid solution hardening effects and will influence the mechanical property of materials.

关键词： edge dislocation doping effect electronic structure.

INTERACTION BETWEEN AN edge dislocation AND A CIRCULAR INCLUSION WITH INTERFACE SLIP AND DIFFUSION

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INTERACTION BETWEEN AN EDGE DISLOCATION AND A CIRCULAR INCLU...

Investigation of reflection anisotropy induced by micropipe defects on the surface of a 4H-SiC single crystal using scanning anisotropy microscopy

第二届亚洲功能材料与结构力学大会

作者： Ernie Pan School of Mechanical Engineering Zhengzhou University Department of Civil Engineering University of Akron

＜正＞We investigate in detail the transient response induced by an edge dislocation near a circular elastic inclusion with simultaneous interface slip and diffusion.A rigorous solution in series form to the interaction problem is *** the time approaches infinity,our solution just recovers the classical one derived by Srolovitz at al.（1984） for fully relaxed boundary *** addition we observe that the edge dislocation will induce a uniform rigid body rotation in the

关键词： edge dislocation Interface diffusion Interface slip Relaxation times Image force

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Chinese Physics B 2024年第3期33卷 630-637页

作者：黄威俞金玲刘雨彭燕王利军梁平陈堂胜徐现刚刘峰奇陈涌海 Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China National Key Laboratory of Solid-state Microwave Devices and Circuits Nanjing Electronic Devices InstituteNanjing 210016China Institute of Micro/Nano Devices and Solar Cells School of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)*** reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by *** RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic *** comparing with the Raman spectrum,it is verified that the micropipes consist of edge *** different patterns of the RA images are due to the different orientations of the Burgers ***,the strain distribution of the micropipes is also *** can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using ***,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect.

关键词： scanning anisotropy microscopy SiC reflection anisotropy edge dislocation