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Title: Stability of Helium Clusters during Displacement Cascades

Abstract

The interaction of displacement cascades with helium-vacancy clusters is investigated using molecular dynamics simulations. The He-vacancy clusters initially consist of 20 vacancies with a Helium-to-vacancy ratio ranging from 0.2 to 3. The primary knock-on atom (PKA) energy, Ep, varies from 2 keV to 10 keV, and the PKA direction is chosen such that a displacement cascade is able to directly interact with a helium-vacancy cluster. The simulation results show that the effect of displacement cascades on a helium-vacancy cluster strongly depends on both the helium-to-vacancy ratio and the PKA energy. For the same PKA energy, the size of helium-vacancy clusters increases with the He/V ratio, but for the same ratio, the cluster size changes more significantly with increasing PKA energy. It has been observed that the He-vacancy clusters can be dissolved when the He/V ratio less than 1, but they are able to re-nucleate during the thermal spike phase, forming small He-V nuclei. When the He/V ratio is larger than 1, the He-V clusters can absorb a number of vacancies produced by displacement cascades, forming larger He-V clusters. These results are discussed in terms of PKA energy, helium-to-vacancy ratio, number of vacancies produced by cascades, and mobility of helium atoms.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
909475
Report Number(s):
PNNL-SA-50941
AT6020100; TRN: US200722%%1102
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1 (SP ISS)):63-67; Journal Volume: 255; Journal Issue: 1 (SP ISS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HELIUM; KNOCK-ON; STABILITY; THERMAL SPIKES; VACANCIES; MOLECULAR DYNAMICS METHOD; ATOMIC DISPLACEMENTS; Fe; displacement cascade; He-vacancy cluster; molecular dynamics; vacancy clusters; stainless-steel; alpha-iron; FE; simulation; metals; MD

Citation Formats

Yang, Li, Zu, Xiaotao T., Xiao, H. Y., Gao, Fei, Heinisch, Howard L., Kurtz, Richard J., Wang, Zhiguo, and Liu, K. Z. Stability of Helium Clusters during Displacement Cascades. United States: N. p., 2007. Web. doi:10.1016/j.nimb.2006.11.064.
Yang, Li, Zu, Xiaotao T., Xiao, H. Y., Gao, Fei, Heinisch, Howard L., Kurtz, Richard J., Wang, Zhiguo, & Liu, K. Z. Stability of Helium Clusters during Displacement Cascades. United States. doi:10.1016/j.nimb.2006.11.064.
Yang, Li, Zu, Xiaotao T., Xiao, H. Y., Gao, Fei, Heinisch, Howard L., Kurtz, Richard J., Wang, Zhiguo, and Liu, K. Z. Thu . "Stability of Helium Clusters during Displacement Cascades". United States. doi:10.1016/j.nimb.2006.11.064.
@article{osti_909475,
title = {Stability of Helium Clusters during Displacement Cascades},
author = {Yang, Li and Zu, Xiaotao T. and Xiao, H. Y. and Gao, Fei and Heinisch, Howard L. and Kurtz, Richard J. and Wang, Zhiguo and Liu, K. Z.},
abstractNote = {The interaction of displacement cascades with helium-vacancy clusters is investigated using molecular dynamics simulations. The He-vacancy clusters initially consist of 20 vacancies with a Helium-to-vacancy ratio ranging from 0.2 to 3. The primary knock-on atom (PKA) energy, Ep, varies from 2 keV to 10 keV, and the PKA direction is chosen such that a displacement cascade is able to directly interact with a helium-vacancy cluster. The simulation results show that the effect of displacement cascades on a helium-vacancy cluster strongly depends on both the helium-to-vacancy ratio and the PKA energy. For the same PKA energy, the size of helium-vacancy clusters increases with the He/V ratio, but for the same ratio, the cluster size changes more significantly with increasing PKA energy. It has been observed that the He-vacancy clusters can be dissolved when the He/V ratio less than 1, but they are able to re-nucleate during the thermal spike phase, forming small He-V nuclei. When the He/V ratio is larger than 1, the He-V clusters can absorb a number of vacancies produced by displacement cascades, forming larger He-V clusters. These results are discussed in terms of PKA energy, helium-to-vacancy ratio, number of vacancies produced by cascades, and mobility of helium atoms.},
doi = {10.1016/j.nimb.2006.11.064},
journal = {Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1 (SP ISS)):63-67},
number = 1 (SP ISS),
volume = 255,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}