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Title: Irradiation hardening of pure tungsten exposed to neutron irradiation

Abstract

In this paper, pure tungsten samples have been neutron irradiated in HFIR at 90–850 °C to 0.03–2.2 dpa. A dispersed barrier hardening model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant hardening contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relatively modest dose (>0.6 dpa). Finally, the precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.

Authors:
 [1];  [1];  [2];  [1];  [3];  [4];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Tohoku Univ., Sendai (Japan)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Inst. for Fusion Science (Japan)
OSTI Identifier:
1327659
Grant/Contract Number:
AC05-00OR22725; SC0006661; NFE-13-04478
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 480; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Hu, Xunxiang, Koyanagi, Takaaki, Fukuda, Makoto, Kumar, N. A. P. Kiran, Snead, Lance L., Wirth, Brian D., and Katoh, Yutai. Irradiation hardening of pure tungsten exposed to neutron irradiation. United States: N. p., 2016. Web. doi:10.1016/j.jnucmat.2016.08.024.
Hu, Xunxiang, Koyanagi, Takaaki, Fukuda, Makoto, Kumar, N. A. P. Kiran, Snead, Lance L., Wirth, Brian D., & Katoh, Yutai. Irradiation hardening of pure tungsten exposed to neutron irradiation. United States. doi:10.1016/j.jnucmat.2016.08.024.
Hu, Xunxiang, Koyanagi, Takaaki, Fukuda, Makoto, Kumar, N. A. P. Kiran, Snead, Lance L., Wirth, Brian D., and Katoh, Yutai. 2016. "Irradiation hardening of pure tungsten exposed to neutron irradiation". United States. doi:10.1016/j.jnucmat.2016.08.024. https://www.osti.gov/servlets/purl/1327659.
@article{osti_1327659,
title = {Irradiation hardening of pure tungsten exposed to neutron irradiation},
author = {Hu, Xunxiang and Koyanagi, Takaaki and Fukuda, Makoto and Kumar, N. A. P. Kiran and Snead, Lance L. and Wirth, Brian D. and Katoh, Yutai},
abstractNote = {In this paper, pure tungsten samples have been neutron irradiated in HFIR at 90–850 °C to 0.03–2.2 dpa. A dispersed barrier hardening model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant hardening contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relatively modest dose (>0.6 dpa). Finally, the precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.},
doi = {10.1016/j.jnucmat.2016.08.024},
journal = {Journal of Nuclear Materials},
number = ,
volume = 480,
place = {United States},
year = 2016,
month = 8
}

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Cited by: 2works
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  • We performed a neutron irradiation to single crystal pure tungsten in the mixed spectrum High Flux Isotope Reactor (HFIR). In order to investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ~90–~800 °C and fast neutron fluences were 0.02–9.00 × 10 25 n/m 2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. Moreover, the hardness and microstructuremore » changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 10 25 n/m 2 (E > 0.1 MeV). Finally, irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 10 25 n/m 2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.« less
  • Influence of helium (He) on the deuterium (D) retention in tungsten (W) under simultaneous He-D plasma exposure was investigated. Bulk polycrystalline tungsten and two W coatings on carbon substrate, namely, plasma-sprayed tungsten and combined magnetron-sputtered and ion implanted tungsten (CMSII-W) were exposed to pure and He-seeded D plasmas generated by electron-cyclotron-resonance plasma source. The D retention in each sample was subsequently analyzed by various methods such as nuclear reaction analysis for the D depth profiling up to 6 {mu}m and thermal desorption spectroscopy for the determination of total amount of D retention. It is shown that seeding of helium intomore » D plasma with helium ion flux fraction of 10% reduces the deuterium retention for all tungsten grades but more significant reduction was observed for polycrystalline W and less significant effect was found for W coatings. From the thermal desorption spectroscopy measurements, we conclude that the presence of He modifies the density of existing traps for D but does not modify the nature of traps. Maximum effect of a reduction in the deuterium retention due to helium seeding was observed at around 500 K for bulk polycrystalline W. Mechanisms of deuterium retention and He effect in different W materials are discussed.« less