Stability of helium bubbles in alpha-iron: A molecular dynamics study

Lucas, Guillaume; Schäublin, R.

doi:10.1016/j.jnucmat.2008.12.128

Cited by 44 publications

(20 citation statements)

References 15 publications

(19 reference statements)

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“…Recently, MD studies of over-pressureized He bubble in Fe suggested the bubble growth mechanism via emission of self-interstitial atoms (SIA), and interstitial type dislocation loops [25][26][27][28][29] . The He bubble growth mechanism in UO 2 is very different from that in Fe, since bonds in oxides are much stiffer and stronger than those in metals making the emission of uranium SIA type defects in oxides not possible.…”

Section: A He Bubbles In Uomentioning

confidence: 99%

Molecular dynamics study of fission gas bubble nucleation in UO2

Liu

Andersson

2015

Journal of Nuclear Materials

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Molecular dynamics (MD) simulations are used to study helium and xenon gas bubble nucleation in UO 2 . For helium bubbles, the pressure release mechanism is by creating defects on the oxygen sublattice. Helium atoms diffuse away from the bubbles into nearby bulk UO 2 , thus forming a diffuse interface. For xenon bubbles, over-pressurized bubbles containing xenon can displace uranium atoms, which tend to aggregate around the xenon bubble as a pressure release mechanism.MD simulations of xenon atoms in pre-existing voids suggest that xenon atoms and the replaced uranium atoms occur in a 1:1 ratio, although kinetic factors may reduce that ratio depending on availability of xenon atoms and vacancies around the bubble. Finally, MD simulations suggest that for small bubbles (1-5 xenon atoms), the xenon bubble nucleus at UO 2 grain-boundaries has much lower formation energy compared to that of bubbles of similar sizes in the bulk. However, when the xenon bubble grows into larger sizes, this energy difference is reduced.1

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Section: A He Bubbles In Uomentioning

confidence: 99%

Molecular dynamics study of fission gas bubble nucleation in UO2

Liu

Andersson

2015

Journal of Nuclear Materials

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“…Based on empirical molecular dynamics (MD) and kinetic Monte Carlo simulations, Morishita et al [15] have demonstrated that the growth and shrinkage of He-vacancy clusters strongly depends on He density in line with our findings. A first-principles simulation has been carried out to examine the stability of small He-vacancy clusters [16] and a further empirical MD study has explored larger clusters with m up to 15 and n up to 5m [17]. With empirical MD simulations, Gao et al [18] have studied the atomic structure of He n V 1 clusters at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Helium bubble nucleation and growth in α-Fe: insights from first–principles simulations

Xiao

Zhang

Lü

2014

J. Phys.: Condens. Matter

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We have carried out a first-principles study on the nucleation and early-stage growth of He bubbles in Fe. The energetics, atomic and electronic structure of He-vacancy complexes, involving both a monovacancy and a nine-vacancy cluster, are examined. Based on the energetics, we then perform thermodynamics analysis to gain deeper insights into He bubble nucleation and growth. We have determined the energy cost for the nucleation of He bubbles and found that up to eight He atoms can be trapped at a single vacancy. In order to capture more He atoms, the vacancy has to emit Frenkel pairs to release the substantial stress building on the surrounding Fe lattice. Compared to the monovacancy, the nine-vacancy cluster has a lower energy cost for He bubble nucleation and growth. He atoms at the vacancy repel the surrounding electronic charge and redistribute it on the neighboring Fe atoms. The thermodynamic analysis reveals that He chemical potential provides a driving force for He bubble nucleation and growth. There are two critical He chemical potentials that are of particular importance: one of them marks the transition from single He occupation to multiple He occupation at a monovacancy while the other sets off He-induced superabundant vacancy formation.

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“…The behavior of He in Fe has been widely investigated [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. MD simulations have been employed to yield important understanding of the behavior of He defects in bcc Fe using different interatomic potentials [2][3][4].…”

Section: Introductionmentioning

confidence: 99%