Reactive Spark Plasma Sintering of Y3Al5O12-MgAl2O4 Composites

Abstract

In this study, Y3Al5O12-MgAl2O4 (YAG-Spinel) composites, with different molar ratios (1:1 and 1:3), were in-situ fabricated via reactive spark plasma sintering technique (RSPS). The Al2O3, MgO, and Y2O3 powders were used as starting materials. In-situ formation of YAG-Spinel composites was investigated according to the reaction 3.5 Al2O3 + MgO + 1.5 Y2O3 → Y3Al5O12 + MgAl2O4. Both synthesis and densification processes were accomplished in a single rsps cycle with one-step heating. The RSPS process was performed at the sintering temperature of 1300 ᵒC for 30 min hold time with a maximum uniaxial pressure of 90 MPa under vacuum conditions. The synthesized phases and microstructures were investigated by X-ray diffraction and field emission scanning electron microscopy. The unwanted phases such as YAP (YAlO3) in composites microstructure were removed using LiF additive. LiF was used as a sintering aid in the process of sintering. The in-situ synthesized YAG-Spinel composites exhibited no internal infrared transmittance over 2.5-25 µm infrared wavelength ranges.