Abstract: Four compositions of nitrogen-containing Dy-melilite solid solutions Dy₂Si_3-xAl_xO_3+xN_4-x (Dy-M’, x=0, 0.3, 0.6 and 1.0) were prepared by hot-pressing
and oxidized at 1000℃ for 20h in air in a TG unit. The weight gains per area of Dy-M’ samples decreased with increasing the Al substitution, i.e.
Dy-M’(x=0.6)<x=0.3)M’, especially for Dy-M’(x=0.6), became better compared with that of Dy-M.
A composition of Dy-α-Sialon with Dy-M’ as the grain boundary phase prepared by hot-pressing was exposed to air at 1000℃ and 1300℃ for
20h. No catastrophic oxidation behavior was observed in the first situation. When the sample was oxidized at 1300℃ for 20h, crystals of
α-Dy₂Si₂O₇ were observed in preferred orientation on the oxidized surface of Dy-α’-M’ sample.

Key words: α-Sialon, melilite, formation, oxidation behavior