Molecular dynamics study of interstitial He clusters in nickel

This study presents a molecular dynamics analysis focusing on the behavior of interstitial helium (He) clusters in nickel (Ni), examining their formation, stability, and migration energetics. We found that the binding energies of interstitial He with a He cluster are positive and increase with the c...

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Main Authors: Giridhar Nandipati, David J. Senor, Andrew M. Casella, Ayoub Soulami
Format: Article
Language:English
Published: Elsevier 2024-12-01
Series:Nuclear Materials and Energy
Online Access:http://www.sciencedirect.com/science/article/pii/S235217912400156X
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author Giridhar Nandipati
David J. Senor
Andrew M. Casella
Ayoub Soulami
author_facet Giridhar Nandipati
David J. Senor
Andrew M. Casella
Ayoub Soulami
author_sort Giridhar Nandipati
collection DOAJ
description This study presents a molecular dynamics analysis focusing on the behavior of interstitial helium (He) clusters in nickel (Ni), examining their formation, stability, and migration energetics. We found that the binding energies of interstitial He with a He cluster are positive and increase with the cluster size, indicating a preference for He atoms to cluster together. While the formation energy increases monotonically with cluster size, binding energy shows non-monotonic. trend Importantly, small He clusters were found to be thermally unstable at reactor operational temperatures (approximately 600 K), with the He2 cluster exhibiting instability even at room temperature. With a binding energy of 0.44 eV for a He4 cluster, we hypothesize that for He bubbles to form via homogeneous nucleation (i.e., through trap mutation) at reactor operating temperatures, the He concentration must be high enough to facilitate the formation of He clusters of at least size 4 or larger. At finite temperatures, He clusters of size 7 and larger trap mutate immediately. However, clusters of size 10 and larger will trap mutate even at 0 K. As expected, interstitial He and small He clusters are highly mobile, and found to be mobile even at temperatures as low as 200 K. Furthermore, the mean squared displacement method has been utilized to determine the activation energies and the corresponding prefactors for clusters ranging from He1 to He6
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spelling doaj-art-aae9664b44864e2bbacd88d0c703e67b2025-08-20T02:40:11ZengElsevierNuclear Materials and Energy2352-17912024-12-014110173310.1016/j.nme.2024.101733Molecular dynamics study of interstitial He clusters in nickelGiridhar Nandipati0David J. Senor1Andrew M. Casella2Ayoub Soulami3Corresponding author.; Pacific Northwest National Laboratory, Richland, WA 99354, USAPacific Northwest National Laboratory, Richland, WA 99354, USAPacific Northwest National Laboratory, Richland, WA 99354, USAPacific Northwest National Laboratory, Richland, WA 99354, USAThis study presents a molecular dynamics analysis focusing on the behavior of interstitial helium (He) clusters in nickel (Ni), examining their formation, stability, and migration energetics. We found that the binding energies of interstitial He with a He cluster are positive and increase with the cluster size, indicating a preference for He atoms to cluster together. While the formation energy increases monotonically with cluster size, binding energy shows non-monotonic. trend Importantly, small He clusters were found to be thermally unstable at reactor operational temperatures (approximately 600 K), with the He2 cluster exhibiting instability even at room temperature. With a binding energy of 0.44 eV for a He4 cluster, we hypothesize that for He bubbles to form via homogeneous nucleation (i.e., through trap mutation) at reactor operating temperatures, the He concentration must be high enough to facilitate the formation of He clusters of at least size 4 or larger. At finite temperatures, He clusters of size 7 and larger trap mutate immediately. However, clusters of size 10 and larger will trap mutate even at 0 K. As expected, interstitial He and small He clusters are highly mobile, and found to be mobile even at temperatures as low as 200 K. Furthermore, the mean squared displacement method has been utilized to determine the activation energies and the corresponding prefactors for clusters ranging from He1 to He6http://www.sciencedirect.com/science/article/pii/S235217912400156X
spellingShingle Giridhar Nandipati
David J. Senor
Andrew M. Casella
Ayoub Soulami
Molecular dynamics study of interstitial He clusters in nickel
Nuclear Materials and Energy
title Molecular dynamics study of interstitial He clusters in nickel
title_full Molecular dynamics study of interstitial He clusters in nickel
title_fullStr Molecular dynamics study of interstitial He clusters in nickel
title_full_unstemmed Molecular dynamics study of interstitial He clusters in nickel
title_short Molecular dynamics study of interstitial He clusters in nickel
title_sort molecular dynamics study of interstitial he clusters in nickel
url http://www.sciencedirect.com/science/article/pii/S235217912400156X
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AT andrewmcasella moleculardynamicsstudyofinterstitialheclustersinnickel
AT ayoubsoulami moleculardynamicsstudyofinterstitialheclustersinnickel