Change in nanoindentation hardness of polycrystalline tungsten irradiated with Fe ions or electrons by hydrogen gas charging

Koichi Sato, Ryuta Kasada, Atsushi Kiyohara, Masashi Hirabaru, Kenichi Nakano, Kiyohiro Yabuuchi, Masahiko Hatakeyama, Qiu Xu

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of hydrogen atoms on the hardnesses of unirradiated, ion-irradiated, and electron-irradiated polycrystalline tungsten samples were investigated using nanoindentation tests. The bulk equivalent hardnesses of the unirradiated and electron-irradiated tungsten samples did not change upon hydrogen charging. The bulk equivalent hardness of the ion-irradiated tungsten increased upon the hydrogen charging. The number of hydrogen atoms trapped at dislocation loops was very small. We estimated that the hydrogen occupancy in vacancy clusters was 0.24−0.45 (in the case of tri-vacancies, the number of hydrogen atoms trapped per vacancy (H/V) is 1.04−1.95). Because of the irradiation temperature of 573 K, the density and size of irradiation-induced defects did not change during hydrogen charging at 543 K. Therefore, the hardening was mainly caused by an increase of approximately 8 − 11% in the obstacle strength α of vacancy clusters containing hydrogen atoms. The ion-irradiated area hardened upon the hydrogen charging and changed the configuration of the pile-up. Observation of the dislocation structure is required to clarify the mechanism of hardening caused by hydrogen charging.

Original languageEnglish
Article number153483
JournalJournal of Nuclear Materials
Volume560
DOIs
Publication statusPublished - 2022 Mar
Externally publishedYes

Keywords

  • Electron irradiation
  • Hardness
  • Hydrogen
  • Ion irradiation
  • Nanoindentation
  • Tungsten

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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