Dislocation structures in a { $$ \bar{1} $$ 104}/〈11 $$ \bar{2} $$ 0〉 low-angle tilt grain boundary of alumina (α-Al2O3)

Abstract

An alumina (α-Al2O3) bicrystal with a ( $$ \bar{1} $$ 104)/[11 $$ \bar{2} $$ 0] 2o low-angle tilt grain boundary was fabricated by diffusion bonding at 1500 °C in air, and the grain boundary was observed by transmission electron microscopy (TEM). High-resolution TEM observations revealed that the grain boundary consists of at least two kinds of dislocations. One is a perfect dislocation which has a Burgers vector of 1/3[ $$ \bar{1} $$ 2 $$ \bar{1} $$ 0]. The other is dissociated into two partial dislocations with a stacking fault on the (0001) plane, and each partial dislocation has a 1/6[ $$ \bar{1} $$ 101] edge component. It is suggested from structural considerations that the dissociated-dislocation pair originates from a b = 1/3[02 $$ \bar{2} $$ 1] perfect dislocation (i.e., 1/3[02 $$ \bar{2} $$ 1] → 1/6[02 $$ \bar{2} $$ 1] + 1/6[02 $$ \bar{2} $$ 1]). This dissociation produces a stacking fault in the anion sublattice. The stacking fault energy is estimated to be roughly 1.3 Jm−2 based on the elastic theory. The authors discuss the dislocation structures and the stacking fault formed on the (0001) plane in detail.