Study on directionally solidified Al₂O₃/Y₃Al₅O₁₂ (YAG) /ZrO₂ hypoeutectic ceramic in situ composite with laser zone remelting

Directionally solidified Al₂O₃/Y₃Al₅O₁₂ (YAG)/ZrO₂ ternary hypoeutectic ceramic in situ composite was prepared by laser zone remelting technique. The relationship between the microstructure and the laser processing parameters was investigated. The solidification behavior and the microstructure formation were analyzed. The results show that: (1) The matching of laser scanning rate and power density determines the quality of the as-solidified composite. With appropriate laser processing parameters, the smooth, level and compact hypoeutectic ceramic without crack and pore can be obtained. (2) The Al₂O₃/YAG/ZrO₂ hypoeutectic ceramic consists of Al₂O₃, YAG and ZrO₂ phases with network structures and the small ZrO₂ phase is distributed at the interface of Al₂O₃ and YAG phases. (3) The solidification microstructure with dendrite structure similar to metal solidification are found in the hypoeutectic ceramic due to the high cooling rate of laser rapid solidification and solute enrichment caused by constituent supercooling.