High-temperature deformation of [00▪1] symmetrical tilt grain boundaries was investigated by using bicrystals. Four types of the grain boundaries, Σ7/{4¯5▪0}, Σ21/{4¯5▪0}, Σ7/{2¯3▪0} and Σ21/{2¯3▪0}, were selected and compression tests were performed at 1450C in air in order to investigate the sliding behavior of the respective boundaries. It was found that the stresses increased with increasing strain for all of the specimens during compression, but the bicrystals exhibited abrupt sliding - along the grain-boundary planes - to fracture. Among the boundaries studied, Σ7/{4¯5▪0} exhibited the highest resistance to grain-boundary sliding. The other boundaries exhibited a similar sliding resistance, but the stress and strain values at failure were much smaller than those of Σ7/{4¯5▪0}. In order to understand the mechanism of the sliding behavior of the respective boundaries, the grain boundary core structures and their atomic densities were examined. It was found that Σ7/{4¯5▪0} had the highest sliding resistance and exhibited a larger atomic density at the core, as compared to the others. Thus, the observed sliding resistance of the boundaries was closely related to the detailed atomic structures at the grain-boundary cores.

High Temperature Deformation Behavior of [0001] Symmetrical Tilt Σ 7 and Σ 21 Grain Boundaries in Alumina Bicrystals. S.Hanyu, H.Nishimura, K.Matsunaga, T.Yamamoto, Y.Ikuhara, T.Sakuma: Materials Transactions, 2004, 45[7], 2122-7