Increased mobility of an α-Al2O3 grain boundary by electron-beam irradiation

When subjected to electron-beam irradiation in a transmission electron microscope, the grain boundary in an α -Al 2 O 3 bicrystal is observed to migrate even at room temperature. The bicrystal is composed of grains with the same normal direction, and thus the difference in strain energy or surface energy between the two grains cannot explain the observed migration. We attribute this phenomenon to an increase in grain boundary mobility by electron-beam irradiation, especially by radiolysis effects.