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 ultrahigh 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 2096 K, matching the phase diagram of Al₂O₃-Y₂O₃ system.