Kinetics of interstitial-type dislocation loops in α-Al2O3 and MgO·Al2O3, which were induced by 6keV Ar+ ions at 300K, was investigated under electron irradiation at 300 to 870K by transmission electron microscopy. Dislocation loops disappeared during electron irradiation at energies of 100, 150 and 200keV, where displacement damage was hardly induced in α-Al2O3 and MgO·Al2O3 with those electron energies. The disappearing rate of dislocation loops increased with decreasing electron energy and with decreasing irradiation temperature. Further, a portion of dislocation loops in α-Al2O3 was found to grow under the sub-threshold energy electron irradiation, and the average size of the surviving dislocation loops decreased with irradiation at 300K but increased at 370, 420 and 570K. It was concluded that dislocation loops in α-Al2O3 and MgO·Al2O3 dissociated into isolated interstitials through ionizing radiation. The generated interstitial was found to recombine mainly with radiation-induced vacancies at lower irradiation temperatures (300K) but to be absorbed to the surviving dislocation loops at higher temperatures (370 to 570K). The disappearing rate of loops was analyzed in terms of a balance between the dissociation process by ionizing radiation and diffusion of the generated interstitials.

Electron-Beam Induced Dissociation of Dislocation Loops in Magnesia–Alumina Ceramics. K.Yasuda, C.Kinoshita: Nuclear Instruments and Methods in Physics Research Section B, 2002, 191[1-4], 559-64