High‐Temperature Deformation and Microstructural Analysis for Silicon Nitride–Scandium (III) Oxide

Limited past studies have indicated that Si 3 N 4 doped with Sc 2 O 3 may exhibit high‐temperature mechanical properties superior to Si 3 N 4 systems with various other oxide sintering additives. High‐temperature deformation of this system was studied by characterizing the microstructures before and after deformation. It was found that elements of the additive, Sc and O, exist in small amounts at thin grain boundary layers and within secondary phases at triple and multiple grain boundary junctions. The secondary phase is devitrified as crystalline Sc 2 Si 2 O 7 . Deformation of the samples was dominated by cavitation rather than dislocation processes. Thus, the excellent deformation resistance of the samples at high temperature can be attributed to the high refractories and enhanced crystallization of a secondary phase.