Microchemical change and grain boundary migration due to excess defects flow under irradiation

A Fe-Cr-Ni model alloy was electron-irradiated using a high voltage electron microscopy (1000kV), and in situ observation on structural evolution and microchemical analyses were carried out. When the Fe-Cr-Ni alloy was irradiated, the nucleation of dislocation loops followed by voids was observed and at the same time a grain boundary migration occurred. The compositional analysis after irradiation of an area including a grain boundary indicated nickel enrichment and chromium depletion near the grain boundary. It is suggested that when the radiation -induced point defects flow into the grain boundary, boundary migration and solutes redistribution are induced and the magnitudes depend on net point defects flow, especially that of interstitial atoms. The microchemical changes were also simulated by model calculation. (author)