IN-SITU OBSERVATION OF MICROSTRUCTURAL DEVELOPMENT DURING ELECTRON-IRRADIATION IN AL2O3 CONTAINING CR2O3 OR TIO2

In order to clarify the effects of Cr3+ and Ti4+ additions on damage s tructural development, pure and 1 mol%Cr2O3- or 1 mol%TiO2-doped Al2O3 have been irradiated with 400 keV electrons at temperatures from 293 to 1273 K. Dislocation loops and plate-shaped cavities are formed on ( 0 0 0 1) planes in the pure A1703 sample. The damaged area, in which t he loops are formed, expands outward from the central part of the elec tron beam during irradiation above 973 K. Although the expansion of th e damaged area is also observed in the Cr2O3-doped sample, the expansi on occurs at higher temperatures of 1073 K and the expansion rate is m uch smaller than that observed in pure sample. Cavities are formed in the Cr2O3-doped sample at a high density compared with the pure sample , but they hardly grow with irradiation dose, resulting in retention o f very small size at higher doses than 7.2 x 10(26) e/m(2). The disloc ation loop and cavity formation in the TiO2-doped sample are similar t o those in the pure sample. (C) 1998 Elsevier Science B.V. All rights reserved.