Yb2O3-fluxed sintered silicon nitride: Part I Microstructure characterization
Microstructural development and crystallization behaviour of Yb 2 O 3 -fluxed sintered silicon nitride materials was investigated using CTEM and HREM. The materials contained 5 and 10 vol % Yb 2 O 3 as sintering additives. After densification, both compositions were subsequently heat treated to crystallize the residual amorphous secondary phases present at triple-grain regions. In the material doped with 5 vol % Yb 2 O 3 , only an amorphous secondary phase was observed after sintering, which was about 80% crystalline (Yb 2 Si 2 O 7 ) after the post-sintering heat treatment.