Electron Radiation Damage of Iron in High Voltage Electron Microscope

Abstract

Aggregation process of irradiation-induced point defects in iron is examined between room temperature and 400°C with a high voltage electron microscope. In the whole temperature range examined interstitial type dislocation loops are formed. The loops formed between slightly above room temperature and 350°C have flower-like shape. Especially the petalous loops formed around 300°C are divided into many small loops at the latter stage of irradiation by absorving mobile vacancies. The formation of the loops in the pre-irradiated specimen also tells that the vacancies become mobile at about 300°C. Analyzing the nucleation of the loops by using the chemical rate theory considering the effects of impurity atoms one obtains the activation energy for interstitial migration as about 0.26 eV.