Crystallization and microstructures of Y-Si-Al-O-N glass-ceramics containing main crystal phase Y3Al5O12

Abstract

A glass with the nominal composition of 28Y48Si24Al83O17N (in equal percentage) was chosen as parent glass in this paper to prepare Y 3 Al 5 O 12 -based glass-ceramics. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to assess the crystallization process of the parent glass. YAG as the only crystalline phase appears in all glass-ceramics produced under 1250°C. A small amount of O′-Sialon secondary phase starts to precipitate from parent glass samples as heat treatment temperature increases to 1250°C. Grain size of the dendrite crystal which corresponds to YAG phase increases and the dendrite branches get thickened as heat treatment temperature increases. Moreover, grain size of YAG phase resulting from two-stage heat treatment is much smaller than that of YAG phase obtained by one-stage heat treatment. The results are relevant to developing improved crystallization treatments for glasses with potential for crystallization to YAG-based glass-ceramics and for heat treatments of YAG/β-SiAlON materials.

In situ synthesis and properties of self-reinforced $$\hbox {Si}_{3} \hbox {N}_{4}\textendash \hbox {SiO}_{2}\textendash \hbox {Al}_{2} \hbox {O}_{3}\textendash \hbox {Y}_{2}\hbox {O}_{3} \ (\hbox {La}_{2}\hbox {O}_{3}$$ Si 3

“…As is known to all, crystallization heat treatments on oxynitride glasses can lead to significant improvements in mechanical properties such as elastic modulus, microhardness, bending strength and fracture toughness. So far, as we know, however, there are only a few previous investigations on crystallization of RE-containing oxynitride glasses [10][11][12][13]. For example, Liddell and Thompson showed that the mixed α-Y 1.5 La 0.5 Si 2 O 7 should be stable before any transformation occurs in a mixed Y-La-Si-Al-O-N glass [14].…”