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Title: Effect of starting microstructure on helium plasma-materials interaction in tungsten

Here, in a magnetic fusion energy (MFE) device, the plasma-facing materials (PFMs) will be subjected to tremendous fluxes of ions, heat, and neutrons. The response of PFMs to the fusion environment is still not well defined. Tungsten metal is the present candidate of choice for PFM applications such as the divertor in ITER. However, tungsten's microstructure will evolve in service, possibly to include recrystallization. How tungsten's response to plasma exposure evolves with changes in microstructure is presently unknown. In this work, we have exposed hot-worked and recrystallized tungsten to an 80 eV helium ion beam at a temperature of 900 °C to fluences of 2 × 10 23 or 20 × 10 23 He/m 2. This resulted in a faceted surface structure at the lower fluence or short but well-developed nanofuzz structure at the higher fluence. There was little difference in the hot-rolled or recrystallized material's near-surface (≤50 nm) bubbles at either fluence. At higher fluence and deeper depth, the bubble populations of the hot-rolled and recrystallized were different, the recrystallized being larger and deeper. This may explain previous high-fluence results showing pronounced differences in recrystallized material. The deeper penetration in recrystallized material also implies that grain boundaries are traps,more » rather than high-diffusivity paths.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 124; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Tungsten; electron microscopy; plasma materials interaction; fusion
OSTI Identifier:
1333665
Alternate Identifier(s):
OSTI ID: 1419147

Wang, Kun, Bannister, Mark E., Meyer, Fred W., and Parish, Chad M.. Effect of starting microstructure on helium plasma-materials interaction in tungsten. United States: N. p., Web. doi:10.1016/j.actamat.2016.11.042.
Wang, Kun, Bannister, Mark E., Meyer, Fred W., & Parish, Chad M.. Effect of starting microstructure on helium plasma-materials interaction in tungsten. United States. doi:10.1016/j.actamat.2016.11.042.
Wang, Kun, Bannister, Mark E., Meyer, Fred W., and Parish, Chad M.. 2016. "Effect of starting microstructure on helium plasma-materials interaction in tungsten". United States. doi:10.1016/j.actamat.2016.11.042. https://www.osti.gov/servlets/purl/1333665.
@article{osti_1333665,
title = {Effect of starting microstructure on helium plasma-materials interaction in tungsten},
author = {Wang, Kun and Bannister, Mark E. and Meyer, Fred W. and Parish, Chad M.},
abstractNote = {Here, in a magnetic fusion energy (MFE) device, the plasma-facing materials (PFMs) will be subjected to tremendous fluxes of ions, heat, and neutrons. The response of PFMs to the fusion environment is still not well defined. Tungsten metal is the present candidate of choice for PFM applications such as the divertor in ITER. However, tungsten's microstructure will evolve in service, possibly to include recrystallization. How tungsten's response to plasma exposure evolves with changes in microstructure is presently unknown. In this work, we have exposed hot-worked and recrystallized tungsten to an 80 eV helium ion beam at a temperature of 900 °C to fluences of 2 × 1023 or 20 × 1023 He/m2. This resulted in a faceted surface structure at the lower fluence or short but well-developed nanofuzz structure at the higher fluence. There was little difference in the hot-rolled or recrystallized material's near-surface (≤50 nm) bubbles at either fluence. At higher fluence and deeper depth, the bubble populations of the hot-rolled and recrystallized were different, the recrystallized being larger and deeper. This may explain previous high-fluence results showing pronounced differences in recrystallized material. The deeper penetration in recrystallized material also implies that grain boundaries are traps, rather than high-diffusivity paths.},
doi = {10.1016/j.actamat.2016.11.042},
journal = {Acta Materialia},
number = C,
volume = 124,
place = {United States},
year = {2016},
month = {11}
}