Al₂O₃/Al₆Ti₂O₁₃ composite ceramics with low thermal expansion properties are promising for the rapid preparation of large-scale and complex components by directed energy deposition-laser based (DED-LB) technology. However, the wider application of DED-LB technology is limited due to the inadequate understanding of process conditions. The shaping quality, microstructure, and mechanical properties of Al₂O₃/Al₆Ti₂O₁₃ (6 mol% TiO₂) composite ceramics were systematically investigated as a function of energy input in an extensive process window. On this basis, the formation mechanism of solidification defects and the evolution process of microstructure were revealed, and the optimized process parameters were determined. Results show that high energy input improves the fluidity of the molten pool and promotes the uniform distribution and full growth of constituent phases, thus, facilitating the elimination of solidification defects, such as pores and strip gaps. In addition, the microstructure size is strongly dependent on the energy input, increasing when the energy input increases. Moreover, the morphology of the α-Al₂O₃ phase gradually transforms from cellular into cellular dendrite with increasing energy input due to changing solidification conditions. Under the comprehensive influence of solidification defects and microstructure size, the fracture toughness and flexural strength of Al₂O₃/Al₆Ti₂O₁₃ composite ceramics present a parabolic law behavior as the energy input increases. Optimal shaping quality and excellent mechanical properties are achieved at an energy input range of 0.36−0.54 W*min² g⁻¹ mm⁻¹. Within this process window, the average microhardness, fracture toughness, and flexural strength of Al₂O₃/Al₆Ti₂O₁₃ composite ceramics are up to 1640 Hv, 3.87 MPa m^1/2, and 227 MPa, respectively. This study provides practical guidance for determining the process parameters of DED-LB of melt growth Al₂O₃/Al₆Ti₂O₁₃ composite ceramics.

具有低热膨胀性能的Al ₂ O ₃ /Al ₆ Ti ₂ O ₁₃复合陶瓷有望通过定向能量沉积-激光（DED-LB）技术快速制备大型复杂部件。然而，由于对工艺条件的了解不够，DED-LB技术的更广泛应用受到限制。Al ₂ O ₃ /Al ₆ Ti ₂ O ₁₃ (6 mol% TiO ₂) 复合陶瓷作为能量输入的函数在广泛的工艺窗口中进行了系统研究。在此基础上，揭示了凝固缺陷的形成机制和组织的演变过程，确定了优化的工艺参数。结果表明，高能量输入提高了熔池的流动性，促进了组成相的均匀分布和充分生长，从而有利于消除气孔和带材间隙等凝固缺陷。此外，微观结构尺寸强烈依赖于能量输入，随着能量输入的增加而增加。此外，α -Al ₂ O ₃的形貌由于凝固条件的变化，随着能量输入的增加，相逐渐从细胞转变为细胞枝晶。在凝固缺陷和微观结构尺寸的综合影响下，Al ₂ O ₃ /Al ₆ Ti ₂ O ₁₃复合陶瓷的断裂韧性和弯曲强度随着能量输入的增加呈现抛物线规律行为。在 0.36-0.54 W*min ² g ^-1 mm ^-1的能量输入范围内实现了最佳的成型质量和优异的机械性能。在此工艺窗口内，Al ₂ O的平均显微硬度、断裂韧性和弯曲强度₃ /Al ₆ Ti ₂ O ₁₃复合陶瓷分别达到1640 Hv、3.87 MPa m ^1/2和227 MPa。该研究为确定熔体生长Al ₂ O ₃ /Al ₆ Ti ₂ O ₁₃复合陶瓷的DED-LB工艺参数提供了实际指导。