Defect structures of F82H irradiated at SINQ using positron annihilation spectroscopy

The growth process of He-filled vacancy clusters during annealing was investigated with positron annihilation lifetime spectroscopy and coincidence Doppler broadening (CDB) measurements. The reduced activation ferritic/martensitic steel F82H was irradiated with high-energy protons and spallation neu...

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Bibliographic Details
Published in:Journal of nuclear materials 2016-01, Vol.468, p.281-284
Main Authors: Sato, K., Ikemura, K., Krsjak, V., Vieh, C., Brun, R., Xu, Q., Yoshiie, T., Dai, Y.
Format: Article
Language:English
Subjects:
Activation
Alloys
Annealing
Clusters
Ferritic stainless steels
Intermetallic compounds
Irradiation
Martensitic stainless steels
Positrons
Trapping
Vacancies
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Summary:The growth process of He-filled vacancy clusters during annealing was investigated with positron annihilation lifetime spectroscopy and coincidence Doppler broadening (CDB) measurements. The reduced activation ferritic/martensitic steel F82H was irradiated with high-energy protons and spallation neutrons. The He-filled vacancy clusters absorbed more He atoms when annealed below 673K, and the long and mean positron lifetimes decreased. When annealed above 873K, the vacancies (V)–Hem or Vn–Hem complexes dissociated (n and m are the number of vacancies and He atoms, respectively). The He-filled vacancy clusters then absorb these dissociated vacancies and He atoms. Therefore, the size of the He-filled vacancy clusters increased, and the He-to-vacancy ratio decreased. These annealing-induced phenomena increased the long positron lifetime in addition to the higher positron trapping rates of the He-filled vacancy clusters. By comparing electron-irradiated samples that did not contain He atoms to the proton- and neutron-irradiated samples containing He atoms, the effects of He atoms on the CDB ratio curves were studied. The results agreed with the previous study of He-ion-implanted Fe–Cr alloys.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2015.03.055