Defect structure and mechanical property changes were studied in 4N-purity Fe, and in Fe-(0.1 or 0.4)%Cr and Fe-(0.1 or 0.4)%Mn alloys, which had been irradiated with neutrons. By comparing the defect structures with yield-strength changes, it was found that a large contribution of invisible defect clusters to irradiation hardening was to be expected in irradiated specimens. Electron irradiation experiments showed that the addition of 0.1% of Cr or Mn to pure Fe tended to suppress the development of large dislocation loops. Frequent nucleation of small loops was observed in the early stages of electron irradiation.

Defect Structure Development in Pure Iron and Dilute Iron Alloys Irradiated with Neutrons and Electrons. A.Okada, H.Maeda, K.Hamada, I.Ishida: Journal of Nuclear Materials, 1999, 271-272, 133-8