Abstract:Rapid surface resolidification with a high powered CO₂-laser was performed in preparing directionally solidified Al₂O₃/YAG/ZrO₂ ternary eutectic ceramic in situ composite. The effects of laser processing parameters on the solidification microstructure characteristics and thermal properties were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD) and synthetically thermal analysis (STA). Detailed investigations of the influence     of laser power and scanning rate on the preparation and microstructural parameters of the ternary eutectic were presented. Moreover, the eutectic phase separation rule at high temperature was discussed. The results indicate that solidification microstructure of     the ternary eutectic composite is greatly influenced by the laser processing parameters. The synthetically thermal analysis shows   that the eutectic temperature of ternary Al₂O₃/YAG/ZrO₂ composite is 1 738 ℃, well matching the phase diagram of Al₂O₃-Y₂O₃-ZrO₂.

Key words: Al₂O₃/YAG/ZrO₂; eutectic in situ composite; ceramic; microstructure; laser resolidification