Abstract: The phase control, mechanical properties and microstructures of α-β-Sialon ceramics were compared among the three counterpart Dy-, Sm-
and (Dy+Sm)-α-β-Sialon compositions. The results show that the dulpex Ln-α-β-Sialon possesses advantage over the single
Ln-α-β-Sialon. Unlike Sm-Sialon, in the (Dy+Sm)-Sialon compositions melilite phase does not occurs during the formation of
α-Sialon. Therefore, the phase compositions based on phase equilibrium can be easily controlled. Sm-Sialons have a rather finer microstructure, higher flexural strength and fracture toughness. These characteristics can
remain in (Dy+Sm)-Sialon ceramics. Dy-Sialons possess a higher hardness and Dy-α’ is much stable than Sm-β’ during heat treatment, which can also
remain in (Dy+Sm)-Sialon ceramics. Therefore, (Dy+Sm)-α-β-Sialon ceramics are quite stable during heat treatment and possesses good mechanical properties.

Key words: Dy, Sm, Sialon, thermal stability, mechanical property