Abstract:The crystallization process of the eutectic composition of GdAlO₃-Al₂O₃ from the amorphous phase prepared by rapid-quenching of melt that leads to the formation of a cantaloupe skin-like microstructure was investigated using focused ion-beam scanning electron microscopy (FIB-SEM) and high-resolution transmission electron microscopy (HR-TEM). The amorphous films were heat-treated at temperatures between 1000 °C and 1500 °C for up to 30 min to form the eutectic phases of GdAlO₃ and Al₂O₃. The GdAlO₃ and Al₂O₃ crystal phases that formed from the amorphous phase were identified by FIB-SEM and HR-TEM. Both components began to crystallize and grow from the amorphous phase separately at different temperatures. The formation process of these crystal phases was different from that of the ordinary eutectic microstructure solidified from the GdAlO₃-Al₂O₃ system. Therefore, the observed structure is termed “eutectic-like” for distinction. The microstructures formed from the amorphous phases at sufficiently high temperatures consisted of ultra-fine microstructures of individually crystallized components and were similar to ordinary eutectic microstructures. By heat-treating the amorphous films at 1500 °C for either 2 min, 8 min or 30 min, the ultra-fine components of GdAlO₃ and Al₂O₃ were found to crystallize following a eutectic-like stage after 8 min of heat treatment.

Key words: eutectic; amorphous; GdAlO₃?Al₂O₃; eutectic-like; HR-TEM; FIB-SEM; Crystallization