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Modelling of Dislocation Bias in FCC Materials
KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.ORCID iD: 0000-0003-4038-7708
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Irradiation induced void swelling is problematic for the application of austenitic steels under high dose irradiation. In this thesis, the swelling is characterized by dislocation bias. The dislocation bias is obtained using the finite element method, accounting for fcc copper and nickel under electron irradiation. The methodology is implemented with the interaction energies between an edge dislocation and point defects. Analytically derived interaction energies, which are based on elasticity theory, are compared with interaction energies obtained from atomistic model using semi-empirical atomic potentials as physics basis. The comparison shows that the description of analytical interaction energies is inaccurate in the dislocation core regions. The bias factor dependence on dislocation density and temperature is presented and discussed. At high temperatures or low dislocation densities, the two approaches tend to converge. However, the dislocation bias based on the interaction energies from the two approaches, reveals larger discrepancy for nickel than for copper. The impact on dislocation bias from the different stacking fault energies of copper and nickel is elaborated. Nickel, which has a larger stacking fault energy, is predicted to have larger swelling rate than copper under the same irradiation conditions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , viii, 33 p.
Series
Trita-FYS, ISSN 0280-316X ; 2013:20
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-122407ISBN: 978-91-7501-785-3 (print)OAI: oai:DiVA.org:kth-122407DiVA: diva2:622175
Presentation
2013-06-12, FA31, Roslagstullsbacken 21, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20130530

Available from: 2013-05-30 Created: 2013-05-20 Last updated: 2013-06-25Bibliographically approved
List of papers
1. Interaction Energy Calculations of Edge Dislocation with Point Defects in FCC Cu
Open this publication in new window or tab >>Interaction Energy Calculations of Edge Dislocation with Point Defects in FCC Cu
2013 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

In order to improve the dislocation bias (DB) model of swelling under irradiation, a large scale of atomistic simulation of the interaction in face centered cubic (FCC) Cu model lattice between an edge dislocation (ED) and point defects such as a vacancy, a self-interstital atom (SIA) have been performed for various configurations. It is found dislocation core splits into partial cores after energy relaxation. Interactions with any SIA conficurations is one order of magnitute larger than with a vacancy. The reason that SIA creats a larger dilatation volumn than the vacancy is directly observed from calculation. Furthurmore, within the interaction range, an octahedron position rather than dumbbell in <100> direction is observed in the stable state after relaxation in interactions between a edge dislocation and a dumbbell SIA. Comparision of interaction energy in analytical and atomistic calculation shows that analytical one has a stronger interaction in vacancy-ED systems, suggesting that the bias factor (BF) from analytical calculation is larger than from atomistic calculation.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-122396 (URN)
Conference
International Conference on Fast Reactors and Related Fuel Cycles: Safe Technologies and Sustainable Scenarios (FR13)
Projects
Generation IV reactor research and development (GENIUS)
Note

QC 20130530

Available from: 2013-05-20 Created: 2013-05-20 Last updated: 2013-05-30Bibliographically approved
2. Dislocation bias factors in fcc copper derived from atomistic calculations
Open this publication in new window or tab >>Dislocation bias factors in fcc copper derived from atomistic calculations
2013 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 441, no 1-3, 357-363 p.Article in journal (Refereed) Published
Abstract [en]

Atomistic calculations were employed in order to calculate the interaction energy of an edge dislocation with different point defects. The bias factor was calculated by applying a finite element method on the interaction energy landscapes obtained from the atomistic calculations. A comparison of the calculated bias factor with a model based on elasticity theory reveals around 30% discrepancy under conditions representative for electron irradiation at 600 degrees C. Possible reasons are discussed. The bias factor dependence on dislocation density and ambient temperature is presented and discussed.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Atomistic calculations, Bias factor, Dislocation densities, Elasticity theory, Interaction energies, Model-based OPC
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-122390 (URN)10.1016/j.jnucmat.2013.06.029 (DOI)000325447600046 ()2-s2.0-84880375938 (Scopus ID)
Projects
Generation IV reactor research and development (GENIUS)
Note

QC 20130718

Available from: 2013-05-20 Created: 2013-05-20 Last updated: 2017-12-06Bibliographically approved

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Chang, Zhongwen

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