Abstract The low fracture toughness of NdYbZr2O7 limits its application as a novel thermal barrier coating (TBC) material. In the present work, NdPO4 was selected to toughen NdYbZr2O7 and the NdPO4/NdYbZr2O7 composites were synthesized by solid-state reaction sintering. Microstructures, fracture toughness and associated toughening mechanisms of the composites were investigated. The fracture toughness of the composite with 20 mol% NdPO4 was ~1.6 MPa m1/2, nearly 25% higher than that of NdYbZr2O7 ceramic. With the addition of NdPO4, the fracture mode transformed from intragranular fracture to a mixed mode of transgranular fracture and intergranular fracture. Besides, several crack propagation paths such as crack bridging, deflection and bifurcation were observed in the NdPO4 grains, indicative of enhanced fracture toughness. Compressive stress in the NdYbZr2O7 matrix, weak NdPO4/NdYbZr2O7 interface and tensile stress in the layered NdPO4 second phase are responsible for the improvement of fracture toughness.

中文翻译：

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NdPO4/NdYbZr2O7 复合材料的断裂韧性提高和多重增韧机制

摘要 NdYbZr2O7 的低断裂韧性限制了其作为新型热障涂层（TBC）材料的应用。在目前的工作中，选择 NdPO4 来增韧 NdYbZr2O7，并通过固态反应烧结合成 NdPO4/NdYbZr2O7 复合材料。研究了复合材料的微观结构、断裂韧性和相关的增韧机制。含有 20 mol% NdPO4 的复合材料的断裂韧性约为 1.6 MPa m1/2，比 NdYbZr2O7 陶瓷高近 25%。NdPO4的加入使断裂模式由沿晶断裂转变为穿晶断裂和沿晶断裂的混合模式。此外，在 NdPO4 晶粒中观察到几种裂纹扩展路径，如裂纹桥接、偏转和分叉，表明断裂韧性增强。