Microstructure and mechanical properties of Al2O3-YSZ and Al2O3-YAG directionally solidified eutectic plates

• Published in: Journal of the European Ceramic Society Vol. 25; no. 8; pp. 1419 - 1429
• Main Authors: LARREA, A, ORERA, V. M, MERINO, R. I, PENA, J. I
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Oxford Elsevier 2005
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Cermets, ceramic and refractory composites; Chemical industry and chemicals; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Miscellaneous; Other materials; Physics; Specific materials; Technical ceramics; Aluminium oxide; Scanning electron microscopy; Composites; Directional solidification; Aluminium Yttrium Oxides Mixed; Mechanical properties; Stabilized zirconia; Al2O3-ZrO2; Experimental study; Oxide ceramics; Composite material; Plate; Fracture toughness; Garnet; Zirconium oxide; Eutectic; Al2O3-YAG; Technical ceramics; Yttrium oxide; Manufacturing; Microstructure; Alumina; Directionally solidified eutectics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2005.01.021

Plates of Al2O3--YSZ and Al2O3--YAG eutectic composition with a thickness from 0*1 to 1mm were prepared by directional solidification using a diode laser stack. The melt processed regions of plates exhibited colony microstructure consisting of finely dispersed phases. Due to the curved shape of the melted pool, the growth rate depends on the distance to the surface plate, decreasing from top to bottom. In this way, the microstructure characteristic length changes as a function of the distance to the plate surface. Vickers indentations and piezo--spectroscopy measurements were done on longitudinal and transverse cross--sections of the samples at different depths. From these measurements, we concluded that the Vickers hardness (HV), indentation fracture toughness (KIC) and residual stresses (sigmah) of the plates were mainly independent from the distance to the surface. The mean values that we obtained in the Al2O3--YSZ plates were HV=16GPa, KIC=4*2MPam(1)(/)(2)and sigmah=--0*33GPa, and in the Al2O3--YAG plates were HV=16GPa, KIC=2*0MPam(1)(/)(2), and sigmah=--0*1GPa. These values are similar to those found in directionally solidified eutectic rods.