Effects of multi-beam irradiation on defect formation in Fe–Cr alloys

Abstract An Fe–8Cr model alloy was irradiated under two modes: simple electron irradiation and dual-beam-irradiation by electrons and helium ions, and in situ observed in the high voltage electron microscope (JEOL JEM-ARM-1300 operated at 1250 kV) at temperatures ranging from 300 to 500 °C. At all temperatures, the size and number density of dislocation loops increased as a function of dose on both specimens. It appears that the dual-irradiated specimens showed greater temperature dependence on the growth rate of dislocation loop than that of electron-irradiated. However, there was little difference in temperature dependence of the saturated loop number density. The migration energy of interstitials was determined to be 0.23 eV for both types of irradiation. The migration energy of vacancies was determined to be 0.95 eV for electron irradiation. From this in situ experiment, it is indicated that the net migration energy of vacancies could be increased due to trapping by helium.