Polycrystalline Al2O3-YAG composites were obtained by using the coprecipitation method. After calcining at different temperatures, the crystallization of YAG was found at about 1000C. Dense bodies could be got by hot-pressing at 1550C. Bending strength and fracture toughness of Al2O3-5vol%YAG and Al2O3-25vol%YAG composites were 604 MPa and 5.0MPa1/2, 611MPa and 4.5MPa1/2 respectively. It indicated that the incorporation of YAG improved the mechanical property of Al2O3 ceramics. Through TEM observation, large YAG particles (about 1mm) located on the grain boundaries of Al2O3 were seen, and some small YAG particles (100200nm) was among Al2O3 grains in both composites. A lot of white areas were found in Al2O3-5vol% YAG composite, which maybe result from the low concentration of yttrium.%用共沉淀法制备了Al2O3-YAG复合粉体，YAG的结晶温度在1000C左右. 共沉淀法制备的Al2O3-YAG复合粉体经1550C热压烧结，获得致密烧结体，YAG的加入量对烧结温度的影响不大. Al2O3-5vol%YAG复合材料的抗弯强度为604MPa，断裂韧性为5.0MPa1/2；Al2O3-25vol%YAG复合材料的抗弯强度为611MPa，断裂韧性为4.5MPa1/2. 所有这些数据都高于单相Al2O3陶瓷的力学性能，说明YAG的加入有利于Al2O3陶瓷力学性能的提高. 通过显微结构观察发现：大的YAG颗粒位于Al2O3晶界上，小的YAG颗粒位于Al2O3晶粒内. 在Al2O3-5vol%YAG复合材料中，许多小的白色区域存在于Al2O3晶粒内，这可能和较低的Y2O3含量有关.
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