Plastic deformation in oxide ceramics. Progress report, January 1, 1977--December 31, 1977

Research on plastic deformation in oxide ceramics has been undertaken. Specifically, the effects of non-stoichiometry on slip on the ''hard'' slip systems in Al-rich Mg--Al spinel and oxygen-rich UO/sub 2 + x/ single crystals is under investigation. In the case of spinel, dislocation structures in both stoichiometric and alumina-rich specimens deformed in compression at elevated temperatures (1500 to 1900/sup 0/C) have been studied using transmission electron microscopy. Unusual dislocation structures are observed after large plastic strains, which are attributed to extensive climb and unique node reactions are observed which are the result of climb dissociation. This climb dissociation is attributed to the presence of large concentrations of vacancies produced by non-conservative dislocation motion