Laser three-dimensional (3D) printing has become a significant technique to fabricate high-performance Al₂O₃-based eutectic ceramics based on melt growth. However, oxygen vacancies are inevitable crystal defects during this process, and their formation mechanism and roles in the as-deposited ceramics are still unclear. In this paper, Al₂O₃/GdAlO₃/ZrO₂ ternary eutectic ceramics were prepared by laser 3D printing, and the formation mechanism of the oxygen vacancies was revealed by conducting a well-designed annealing experiment. In addition, the effects of the oxygen vacancies on the structure and mechanical property of the as-solidified eutectic ceramic were investigated. The formation of oxygen vacancies is revealed to be a result of the transfer of oxygen atoms from the oxide ceramic to the oxygen-deficient atmosphere by means of vacancy migration mechanism. Besides, the presence of oxygen vacancies has no obvious effects on crystalline structure and microstructure of the additively manufactured eutectic ceramic. However, the chemical bond property changes to some extent due to the formation of these crystal defects, which may affect the mechanical property of the as-deposited eutectic ceramic. It is found that the hardness decreases by 3.9%, and the fracture toughness increases by 13.3% after removing the oxygen vacancies. The results may provide a potential strategy to regulate the mechanical property of the oxide ceramic materials.

激光三维（3D）打印已成为基于熔体生长制造高性能Al ₂ O ₃基共晶陶瓷的重要技术。然而，氧空位是这一过程中不可避免的晶体缺陷，其形成机制和在沉积态陶瓷中的作用仍不清楚。本文采用激光3D打印技术制备了Al ₂ O ₃ /GdAlO ₃ /ZrO ₂三元共晶陶瓷，并通过精心设计的退火实验揭示了氧空位的形成机理。此外，还研究了氧空位对凝固态共晶陶瓷的结构和力学性能的影响。氧空位的形成被揭示是氧原子通过空位迁移机制从氧化物陶瓷转移到缺氧气氛的结果。此外，氧空位的存在对增材共晶陶瓷的晶体结构和显微结构没有明显影响。然而，由于这些晶体缺陷的形成，化学键性能会发生一定程度的变化，这可能会影响沉积态共晶陶瓷的力学性能。结果发现，去除氧空位后，硬度降低了3.9%，断裂韧性提高了13.3%。研究结果可能为调节氧化物陶瓷材料的机械性能提供潜在的策略。