Defect structure development in a pure iron and dilute iron alloys irradiated with neutrons and electrons

The defect structure and mechanical property changes were observed for pure iron of 99.99% purity and a series of Fe-(0.1% and 0.4%) Cr and Fe-(0.1% a nd 0.4%) Mn dilute alloys irradiated with neutrons. From the comparison of the defect structures with yield strength change, a large contribution of t he invisible defect clusters to the irradiation hardening was expected in t he specimens irradiated in Japan Materials Test Reactor (JMTR), whereas the se clusters are not found after irradiation in the Fast Flux Test Facility (FFTF). The electron irradiation experiments showed that addition of chromi um and manganese to 0.1% in pure iron, development of large dislocation loo ps is suppressed, and frequent nucleation of small loops at the early stage of the electron irradiation is observed, similar to that in ultra-high pur ity iron of 99.9999% purity. The mechanisms of dislocation loop development in the early stage of irradiation for Fe-Cr and Fe-Mn are considered to be different. (C) 1999 Elsevier Science B.V. All rights reserved.