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 〈101¯0〉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.