Preferential growth of directionally solidified Al₂O₃/SmAlO₃ eutectic ceramics

Directionally solidified Al₂O₃/SmAlO₃ (SAP) eutectic ceramics were successfully prepared with an optical floating zone furnace. The crystallographic orientation and interfacial structures were investigated by electron backscattered diffraction and transmission electron microscopy. It was found that Al₂O₃ has one preferred growth direction but the SAP has two. The preferred growth direction of the directionally solidified Al₂O₃/SAP eutectic ceramics was ⟨1010⟩ Al₂O₃ || ⟨100⟩SAP || ⟨011⟩ SAP. The near-coincidence site lattice models were proposed to interpret the intergrowth of the two SAPs. It was found that the two interfaces have nearly the same volume strain, validating the coexistence of both orientation relationships.