Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

Makoto Fukuda, N. A.P. Kiran Kumar, Takaaki Koyanagi, Lauren M. Garrison, Lance L. Snead, Yutai Katoh, Akira Hasegawa

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)


Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). 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 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure 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 × 1025 n/m2 (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (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.

Original languageEnglish
Pages (from-to)249-254
Number of pages6
JournalJournal of Nuclear Materials
Publication statusPublished - 2016 Oct 1


  • HFIR
  • Irradiation hardening
  • JMTR
  • Joyo
  • Microstructure
  • Neutron irradiation
  • Neutron spectrum effect
  • Tungsten

ASJC Scopus subject areas

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


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