Longitudinal cross-section microstructure of growth striation in Al2O3/Y3Al5O12/ZrO2 directionally solidified eutectic ceramic prepared by laser floating zone

Periodic growth striations with a width of 380 μm are observed in Al2O3/Y3Al5O12/ZrO2 ternary directionally solidified eutectic ceramic prepared by laser floating zone. It is found that the microstructure of the growth striations exhibits disparate growth characteristics. The direct experimental evidence of the formation of the microstructure of the growth striations is obtained through examining the solid–liquid interface. The lamellar coarsening of the growth striations is related to the nucleation of Al2O3 particles and their engulfment by the extended Y3Al5O12 phase. The mechanism accounting for this phenomenon is explained by considering eutectic growth behavior under mutative condition induced by oscillatory convection.