Broadening the microstructure regime of Al2O3–ZrO2 hypereutectic ceramic fabricated via laser powder bed fusion

Abstract

The microstructure and mechanical property regime of laser powder bed fusion fabricated Al₂O₃–ZrO₂ hypereutectic ceramic samples were thoroughly investigated by tailoring the printing parameters. The findings indicate that both the hypereutectic and eutectic microstructure are obtained depending on the varying printing parameters. The ZrO₂ dendrites in the hypereutectic structure gradually refine as the laser energy density increases, while the surrounding eutectic structure evolves continuously. The uniform eutectic microstructure is developed until the dendrites disappear. Simultaneously, it is observed that coarse Al₂O₃ particles were formed in the overlap part of the eutectic structure where the laser energy is higher. In terms of mechanical properties, the samples with alumina particles in the eutectic microstructure have a maximum hardness of 1616.13 HV, while the sample with uniform eutectic microstructure has the highest fracture toughness of 5.87 MPa⋅m^1/2. These findings can contribute to the introduction of a unique microstructure in Al₂O₃–ZrO₂ ceramic.