Study of damage in binary Fe85Cr15 alloys irradiated by ions and the effect of an external magnetic field during irradiation Articles uri icon

publication date

  • April 2019

start page

  • 138

end page

  • 147

volume

  • 517

international standard serial number (ISSN)

  • 0022-3115

electronic international standard serial number (EISSN)

  • 1873-4820

abstract

  • Understanding radiation-induced damage in iron-chromium alloys is critical for the use of advanced steels in future fusion reactors. However, the role of the strong magnetic fields present in such magnetically confined plasma devices on material damage, though considered important, has not been thoroughly explored to date. In this work, irradiation experiments of Fe85Cr15 alloy (15% Cr content) by heavy (Fe+) and light (He+) ions have been carried out in order to characterize the damage and, additionally, the influence of an external magnetic field (B = 0.4 T) has been taken into account. The analysis of the data has been done with different techniques, the distribution of the Cr and/or vacancies around probe nuclei has been explored by Mossbauer spectroscopy and the vacancy profile by Slow Positron Annihilation Spectroscopy (SPAS). Comparison between samples irradiated by He+ and Fe+, in absence of B, reveals significant differences in the average hyperfine magnetic field ( = 0.8 T). This can be attributed to changes in the local environment around the probe nuclei (Fe-57) where either vacancies or the Cr distribution play a role. From depth-profiling by SPAS in Fe thorn irradiated samples, a large concentration of vacancy-type defects is found with a profile that extends deeper than that predicted by computer simulations. Furthermore, sequential irradiation by Fe+ and He+ ions indicates that the He atoms tend to fill the vacancy clusters just in the depth where the He+ is implanted. On the other hand, small but significant differences in vacancy-type defect profiles are found between the samples irradiated both in the presence and absence of a magnetic field (B = 0.4 T) both independently of single and sequential irradiation. Detailed Mossbauer spectroscopy and SPAS analysis seem to point out that external magnetic fields could be a non-negligible parameter in the material damage due to ion irradiation. (C) 2019 Elsevier B.V. All rights reserved.

keywords

  • fusion materials; fe-cr alloys; magnetism; displacement damage; mossbauer spectroscopy; slow positron annihilation spectroscopy; fe-cr alloys; neutron; steels