Grain Boundary Sliding and Atomic Structures in Alumina Bicrystals with [0001] Symmetric Tilt Grain Boundaries

Abstract

Orientation controlled alumina bicrystals were fabricated by a hot joining technique at 1773 K in air to obtain [0001] symmetric tilt boundaries including coincidence grain boundaries. The grain boundary energies were measured by the thermal grooving technique, and they were found to strongly depend on the grain boundary character. Atomic structures of those grain boundaries were observed by high-resolution electron microscopy (HREM). It was found that the atomic structures did not always correlate with the grain boundary energies. This finding indicates that the grain boundary energy originates not only from the atomic bonding on the grain boundary but also from the strain of the grain interior in the vicinity of the boundary. The grain boundary sliding was also investigated by the high-temperature creep test. As the results, the grain boundaries with the same energy showed different sliding behavior. The occurrence of grain boundary sliding is considered to depend on the atomic bonding of a grain boundary.