<i>In situ</i>study of self-ion irradiation damage in W and W–5Re at 500 °C

Yi, Xiaoou; Jenkins, M. L.; Briceno, Martha; Roberts, Steve; Zhou, Zheng; Kirk, Marquis A.

doi:10.1080/14786435.2012.754110

Cited by 141 publications

(145 citation statements)

References 46 publications

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“…Recent experimental observations suggested that large interstitial clusters may be formed within individual cascades during in situ TEM with 150-keV self-ion irradiation in W [18]. The formation of such clusters is presumed to be an athermal process.…”

Section: Discussionmentioning

confidence: 99%

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

Setyawan

Nandipati

Roche

et al. 2015

Journal of Nuclear Materials

110

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Molecular dynamics simulations have been used to generate a comprehensive database of surviving defects due to displacement cascades in bulk tungsten. Twenty one data points of primary knock-on atom (PKA) energies ranging from 100 eV (sub-threshold energy) to 100 keV (∼780×E d , where E d is the average displacement threshold energy) have been completed at 300 K, 1025 K and 2050 K. Within this range of PKA energies, two regimes of power-law energy-dependence of the defect production are observed. A distinct power-law exponent characterizes the number of Frenkel pairs produced within each regime. The two regimes intersect at a transition energy which occurs at approximately 250×E d . The transition energy also marks the onset of the formation of large self-interstitial atom (SIAs) clusters (size 14 or more). The observed defect clustering behavior is asymmetric, with SIA clustering increasing with temperature, while the vacancy clustering decreases. This asymmetry increases with temperature such that at 2050 K (∼0.5T m ) practically no large vacancy clusters are formed, meanwhile large SIA clusters appear in all simulations. The implication of such asymmetry on the long-term defect survival and damage accumulation is discussed. In addition, rare <100>{110} SIA loops are observed.

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Section: Discussionmentioning

confidence: 99%

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

Setyawan

Nandipati

Roche

et al. 2015

Journal of Nuclear Materials

110

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“…Recent experimental observations suggest that small dislocation loops may be formed within individual displacement cascades during in-situ TEM with 150-keV self-ion irradiation of W [1], which stimulates fundamental questions on how the formation of these extended defects and other defect distributions are related to the underlying cascade morphology. Furthermore, it is also an interesting question to determine whether morphological transition exists as a function of energy.…”

Section: Introductionmentioning

confidence: 99%

Cascade morphology transition in bcc metals

Setyawan

Selby

Juslin

et al. 2015

J. Phys.: Condens. Matter

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Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (NF ∼ E b M D ). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, µ, between the high-and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of µ as a function of displacement threshold energy, E d , is presented for bcc metals.

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“…A common issue with this purely viscous dynamical law is the absence of any temperature and thus thermal fluctuations. It has recently been shown 4,5 that to correctly capture the highly stochastic trajectories of nano-scale defects and kink-bearing dislocation lines seen in experiment 6,7 one must also add a stochastic thermal force η(t) to the defect equation of motion, giving the Langevin equation…”

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confidence: 99%

Phonon drag force acting on a mobile crystal defect: Full treatment of discreteness and nonlinearity

Swinburne

Dudarev

2015

Phys. Rev. B

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Phonon scattering calculations predict the drag force acting on defects and dislocations rises linearly with temperature, in direct contradiction with molecular dynamics simulations that often finds the drag force to be independent of temperature. Using the Mori-Zwanzig projection technique, with no recourse to elasticity or scattering theories, we derive a general Langevin equation for a crystal defect, with full treatment of discreteness and non-linearity in the defect core. We obtain an analytical expression for the drag force that is evaluated in molecular statics and molecular dynamics, extracting the force on a defect directly from the inter-atomic forces. Our results show that a temperature independent drag force arises because vibrations in a discrete crystal are never independent of the defect motion, an implicit assumption in any phonon-based approach. This effect remains even when the Peierls barrier is effectively zero, invalidating qualitative explanations involving the radiation of phonons. We apply our methods to an interstitial defect in tungsten and solitons in the Frenkel-Kontorova model, finding very good agreement with trajectory-based estimations of the thermal drag force.

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In situstudy of self-ion irradiation damage in W and W–5Re at 500 °C

Cited by 141 publications

References 46 publications

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

Cascade morphology transition in bcc metals

Phonon drag force acting on a mobile crystal defect: Full treatment of discreteness and nonlinearity

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