光悬浮区熔定向凝固Al2O3/YAG共晶陶瓷微观结构与力学、热学性能各向异性关系研究

Directionally solidified Al2O3/YAG eutectic in situ composites are considered as promising candidates for new generation high-temperature structural ceramics due to its good high temperature creep resistance, high temperature strength, high temperature stability and oxidation resistance. Its unique microstructure features (anisotropy of eutectic domains, growth orientation and relative crystallographic), resulting in the anisotropic mechanical and thermal properties. The present developments could not provide clearly explanation to the relationship between the microstructure and the anisotropic mechanical and thermal properties. The project intends to process Al2O3/YAG eutectic composites by a modified floating zone method at different solidification conductions to change the microstructure dimensions, and then investigates the relationship between the microstructures and its anisotropic mechanical (strength, fracture toughness, deformation behavior and fracture mechanisms, etc.) and thermal (thermal expansion, thermal conductivity and thermal shock resistance, etc.) properties, and to understand the impacts of micro-structural characters on its mechanical and thermal properties. The present project will reveal the intrinsic relationship between solidification conditions, microstructures and the anisotropic mechanical and thermal properties. It will also establish fundamental guidelines to optimize the mechanical and thermal performance of Al2O3/YAG eutectic in situ composites by tailoring the solidification conditions and microstructures. We expect that the obtained results will be helpful for understanding and developing new alumina-based eutectic in situ composites.

定向凝固Al2O3/YAG共晶自生复合陶瓷具有优异的高温抗蠕变性、高温强度、高温稳定性和抗氧化性，是极具潜力的新型高温结构材料。其独特的显微结构（凝固组织定向生长、存在晶体学取向）导致了材料各向异性的力学和热学性能。迄今为止其显微结构对力学、热学性能各向异性的影响机制尚不清楚。本项目拟采用自主改进的光悬浮区熔炉，研究不同凝固条件下Al2O3/YAG共晶陶瓷中微观组织与其力学（强度、断裂韧性、变形行为和断裂机制等）和热学（热膨胀、热导率和抗热震性等）性能各向异性的联系，探索微观组织对其力学、热学性能各向异性的影响机制。本项目的研究结果将揭示不同凝固条件下，材料的微观组织以及力学、热学性能变化规律，对于优化凝固参数和微观组织，获得性能优异的Al2O3/YAG共晶自生复合材料，具有重要的科学价值和现实意义，同时对于理解和开发新型氧化铝基共晶自生复合陶瓷具有普适的参考和借鉴价值。

定向凝固Al2O3/YAG共晶自生复合陶瓷具有优异的高温抗蠕变性、高温强度、高温稳定性和抗氧化性，是极具潜力的新型高温结构材料。其独特的显微结构（凝固组织定向生长、存在晶体学取向）导致了材料各向异性的力学和热学性能。迄今为止其显微结构对性能的影响机制尚不清楚。本项目采用自主改进的光悬浮区熔炉，探索了光悬浮区熔法制备Al2O3/YAG 共晶的工艺，成功制备了单晶Al2O3/YAG 共晶。研究了定向凝固过程中Al2O3/YAG 共晶凝固速率与共晶组织之间的关系和凝固领先相，根据其生长特性建立了生长模型，分析了共晶的组织结构演化、三维空间组织结构和择优取向及单晶相界面结构；研究了定向凝固Al2O3/YAG 共晶的硬度、断裂韧性、室温弯曲强度和压缩强度等力学性能。本项目的研究结果揭示了不同凝固条件下，材料的微观组织以及性能变化规律，对于优化凝固参数和微观组织，获得性能优异的Al2O3/YAG共晶自生复合材料，具有重要的科学价值和现实意义，同时对理解和开发新型氧化铝基共晶自生复合陶瓷具有普适的参考和借鉴价值。