Twist angle dependence of interfacial fracture toughness of (0001) twist boundary of alumina

The influence of the twist angle on the fracture toughness of (0001) twist boundary of alumina was investigated using alumina bicrystals. The alumina bicrystals were fabricated by joining two single crystals which were rotated relative to each other around the <0001> axis with the specific twist angles. Interfacial fracture toughness of alumina bicrystals was measured by single edge V-notched tension test. It was shown that the fracture toughness of (0001) twist boundary of alumina varied from 1 Jm(-2) to 22 Jm(-2) depending on the twist angle. Furthermore, the interfacial fracture toughness also depended on the crack propagating direction. The experimental results were discussed in relation to the change in surface energy, boundary energy and plastic dissipative energy.