Alumina-YAG composites: preparation, experimental characterization and numerical modelling

Al2O3/YAG composite powders have been synthesised by reverse strike precipitation. The powders were characterised by DTA/TG simultaneous analysis; the phase evolution was studied by XRD analysis, while the crystallite formation and growth were followed by TEM observations. A fully dense, homogenous material was obtained by sintering 900°C pre-treated powders at 1600°C for 3 h. For limiting grain growth, both a doping with 500 ppm MgO followed by a free sintering and a fast sintering procedure involving a high heating rate (50°C/min) were performed. The sintered bodies were then characterised by SEM observation and Vickers indentation. Moreover, a numerical model was employed in order to estimate the mechanical properties of the composite materials starting from their microstructural features and from the single constituent phase properties.