Experimental comparison of the (ODS)EUROFER steels implanted by helium ions and irradiated in spallation neutron target

The microstructure of EUROFER and ODS-EUROFER has been characterized by means of positron annihilation spectroscopy (PAS) with a particular focus on the effect of irradiation conditions. Two different irradiation experiments have been used to introduced helium-filled cavities in the studied material...

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Bibliographic Details
Published in:Journal of nuclear materials 2019-09, Vol.523, p.51-55
Main Authors: Krsjak, V., Degmova, J., Veternikova, J. Simeg, Yao, C.F., Dai, Y.
Format: Article
Language:English
Subjects:
Coalescence
Coalescing
Dispersion hardening steels
Eurofer
Gas-filled cavities
Genetic transformation
Helium
Helium bubbles
Helium ions
Irradiation
Irradiation effects in solids
ODS Eurofer
Positron annihilation
Positron beams
S parameters
Spallation
Spallation targets
Spectroscopy
Spectrum analysis
Steel
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Summary:The microstructure of EUROFER and ODS-EUROFER has been characterized by means of positron annihilation spectroscopy (PAS) with a particular focus on the effect of irradiation conditions. Two different irradiation experiments have been used to introduced helium-filled cavities in the studied materials. Materials irradiated in spallation neutron target SINQ have been investigated by conventional positron annihilation spectroscopy, while helium-implanted samples of the same materials have been investigated by slow positron beam technique. With this approach, we were able to obtain a significant amount of positron lifetime and Doppler broadening data and evaluate them with respect to the dpa, irradiation temperature and helium concentration effects. Both types of irradiation experiments confirm a more pronounced creation of growing open-volume defects for the Eurofer steel, comparing to its ODS variant. The bubble-to-void transformation was indirectly but clearly confirmed by the Eurofer specimens. In the case of the ODS Eurofer, the coalescence of helium bubbles, accompanied by saturation of positron mean-lifetime and/or S parameter, was not so evident. This present study provides the first experimental positron annihilation data, showing the onset of void formation in ODS steels.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2019.05.044