Microstructural and mechanical analysis of (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 high-entropy oxide ceramic fabricated in-situ via laser powder bed fusion

High-entropy ceramics (HECs) have gained attention for their exceptional properties, yet their manufacturing techniques face challenges of long cycles and complex processes. Laser powder bed fusion (LPBF) technology has the potential to address these challenges. In this study, the phase composition, microstructure, crystallography, density, and hardness were investigated at various scanning speeds. The findings reveal that (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 (RE3Al5O12) were in-situ synthesized via LPBF. Samples deposited at varying scanning speeds exhibited RE3Al5O12 phase with dendritic morphologies, showing notable enrichment of Al, O, and Eu elements at inter-dendritic and grain boundary. The interior of dendrites has been confirmed to be a garnet-structured high-entropy phase, and it is inferred that the segregation may consist of incompletely reacted Al2O3 and an intermediate phase of (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3AlO3 (REAlO3). Density, pore morphology, and grain size changed with scanning speed, achieving a density of 97.83 % ± 0.55 % at 60 mm/s. Hardness peaked at 15.09 ± 0.68 GPa at 120 mm/s.