激光快速熔凝Al2O3/YAG共晶陶瓷的制备与组织

采用激光快速熔凝技术制备Al₂O₃/YAG共晶自生复合陶瓷, 研究Al₂O₃/YAG共晶陶瓷在高能激光束作用下,不同扫描速率(0.01~2.0mm/s)、超高温度梯度下的凝固组织特征及其生长机制,探索激光熔凝过程控制参数与凝固组织的关系.研究结果表明:激光熔凝Al₂O₃/YAG共晶陶瓷由无规则连续分布的Al₂O₃相和YAG相两相组成,没有晶界和其他相,Al₂O₃相的体积分数为(45.0±2.0)%,两相耦合生长,交错分布,是典型的快速凝固层片状非规则共晶组织;共晶层间距细密, 并随激光扫描速度的增大而减小,扫描速度为0.02mm/s 时,共晶间距约为1~2μm,扫描速度为2.0mm/s时,共晶间距仅为0.5μm左右;综合热分析表明,Al₂O₃/YAG共晶熔点为2096K,与相图吻合.

Processing and microstructure of Al2O3/YAG eutectic ceramic by laser rapid remelting

Laser rapid remelting experiments were conducted on the preparation of Al₂O₃/YAG eutectic ceramic in-situ composite to investigate the microstructure characteristic and growth behavior under an ultra-high temperature gradient and different laser scanning rates of 0.01~2.0mm/s, and to explore the relationship between the laser processing parameters and the microstructure. The results show that the laser remelted Al₂O₃/YAG eutectic is composed of irregularly and continuously distributed Al₂O₃ and YAG phases without grain boundary and any other phase. The volume fraction of Al₂O₃ is (45.0±2.0)%. The two phases couple each other and complexly interweave, in which the microstructure belongs to the typical lamellar structure of rapidly solidified anomalous eutectic. The eutectic spacing is very small and decreases from about 1~2μm to 0.5μm as the laser scanning rate increases from 0.02~2.0mm/s. The synthetical themal analysis(STA) shows that the eutectic temperature of Al₂O₃/YAG is 2096K, matching the phase diagram of Al₂O₃-Y₂O₃ system.