Defect-flow-induced grain boundary migration with segregation under electron irradiation

Abstract

An Fe-Cr-Ni alloy was electron-irradiated using a high voltage electron microscope (1 MV), and in situ observations on the structural evolution and microchemical analysis were carried out. The compositional analysis showed that under irradiation an area near a grain boundary was nickel-enriched and chromium-depleted, and that, simultaneously, grain boundary migration occured. Moreover, the distance of the grain boundary migration increased almost linearly with the degree of segregation, and the migration occured predominantly in the direction perpendicular to close-packed crystal planes. Underpinned with computer calculations, it is suggested that when the radiation-induced point defects flow into the grain boundary, boundary migration and solute redistribution occur. Furthermore, the magnitude of the effects depends on the net point defect flow, especially that of interstitial atoms.