DISLOCATION EVOLUTION IN A MODEL AND A CANDIDATE FERRITIC ALLOY DURING STEADY AND VARYING TEMPERATURE ELECTRON IRRADIATIONS

Dislocation loop formation and evolution in a Fe-10 Cr and JLF-5 (low activation ferritic alloy) during 1 MeV electron irradiation were inve stigated at constant and varying temperatures. The type of loops (Burg ers vector and plane) formed was found to be sensitive to irradiation temperature. In the case of low temperature irradiation followed by hi gh temperature irradiation, the loop type was similar to that by irrad iation at the low temperature only. In Fe-10 Cr, this rule was obeyed even when the period of the first low temperature irradiation was very short (e.g. 15 s, 0.003 dpa). In JLF-5, longer irradiation at the low temperature is needed to affect the type of loops. It was shown that, in ferritic alloys, the fraction of Burgers vector of dislocations an d relating void swelling at high fluence would be strongly influenced by short-term negative temperature excursion in the initial period of the irradiation.