Study Of Grain Boundary Migration In Alumina

The sintering process of ceramics involves mass transport across grain boundaries resulting in the migration of these boundaries. When there is a liquid at the interface-as in liquid-phase sintering-the mass transport can be enhanced. In this study, electron backscatter diffraction (EBSD) has been used to examine grain-boundary migration (GBM) of controlled interfaces in alumina. The interfaces were prepared by liquid-phase sintering single-crystal and polycrystalline alumina to single-crystal substrates of known orientation. EBSD patterns, taken near the sintered interfaces, have been used to study the effects of crystallography on GBM and to study the orientation relationships within the migrated regions. Results indicate that migration of the controlled interfaces occurs only when the bounding planes are different, and that the direction of migration is not always the same as that predicted by the current theories on GBM.