Fabrication of Y3Al5O12-Al2O3 eutectic materials having ultra fine microstructure

A mixture of Y2O3 and Al2O3 with a eutectic composition was melted and quenched rapidly to form an amorphous phase. A eutectic microstructure, which was formed from the amorphous phase, was investigated. A heat-treatment of the amorphous phase at 1000 °C and 1300 °C for 30 min formed an Y3Al5O12 (YAG: Yttrium Aluminium Garnet)-Al2O3 eutectic microstructure. The eutectic microstructure, which was formed from the amorphous phase at 1300 °C for 30 min, was ultra fine. The amorphous film was pulverized and sintered both by conventional sintering and Spark Plasma Sintering (SPS). Following conventional sintering the eutectic microstructures of the conventionally sintered specimens became coarse. By using the conventional sintering method, a high sintering temperature (1600 °C) and long sintering time (24 h) was required to form dense specimens. This resulted in grain growth. On the contrary, the SPS sintered body had an ultra fine eutectic microstructure with a high bulk density. SPS was successful in suppressing grain growth.