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采用激光悬浮区熔定向凝固方法制备了高致密度Al_2O_3/YAG/ZrO_2共晶自生复合陶瓷材料,研究多元复相陶瓷在高温度梯度、不同生长条件下的凝固组织形态演化规律,定量表征凝固速率与氧化物陶瓷共晶间距的关系,在此基础上,考察其力学性能并分析凝固组织与断裂韧性的关系.研究结果表明:激光悬浮区熔Al_2O_3/YAG/ZrO_2三元自生复合材料呈现与热流方向平行、定向性良好的非规则层片共晶形貌,共晶组织随凝固速率的增大而快速细化,凝固速率为200μm/s时,最小层片间距达到0.46μm.平均层片间距λav与凝固速率V之间符合关系:λ_(av)V~(0.5)=12.4μm~(1.5)·s~(-0.5),且明显小于同等凝固速率条件下Al_2O_3/YAG二元共晶的平均层片间距.Al_2O_3/YAG/ZrO_2三元共晶平均硬度为(19.0±1.0)GPa,室温断裂韧性为(3.31±0.2)MPa·m~(1/2).与二元共晶相比,裂纹捕获、偏转以及共晶相热胀系数失配是三元共晶室温断裂韧性提高的主要原因.
The high density Al_2O_3 / YAG / ZrO_2 eutectic self-forming ceramic composite material was prepared by laser solidification method in the suspension zone of the laser. The morphology and microstructure evolution of the multiphase composite ceramics were studied under high temperature gradient and different growth conditions. The solidification rate And the relationship between the eutectic spacing of the oxide ceramics and the mechanical properties of the composites were also investigated.The results show that the Al3O4 / YAG / ZrO2 composites exhibit the same properties as the heat flux The eutectic morphology of eutectic lamellae with parallel orientation and good directivity was obtained. The eutectic microstructure was refined rapidly with the increase of the solidification rate. When the solidification rate was 200μm / s, the minimum interlamellar spacing was 0.46μm. The relationship between the λav and the solidification rate V is as follows: λ av av 0.5 = 12.4 μm 1.5 s -0.5, which is obviously lower than that of Al 2 O 3 / YAG binary eutectic under the same solidification rate Average interlayer spacing, the average hardness of ternary eutectic Al 2 O 3 / YAG / ZrO 2 was (19.0 ± 1.0) GPa and the room temperature fracture toughness was (3.31 ± 0.2) MPa · m -1 .Compared with binary eutectic , Crack capture, deflection and eutectic phase thermal expansion coefficient mismatch is ternary Room temperature fracture toughness is the main reason.