Synergistic enhancement of densification efficiency and radiation resistance in NITE-SiC via nitrogen-doped quaternary additives

This study investigates the densification, mechanical properties, and irradiation response of NITE-SiC fabricated using two low-content quaternary sintering additive systems: AlN-Y 2 O 3 -CeO 2 -MgO (AN-SiC) and Al 2 O 3 -Y 2 O 3 -CeO 2 -MgO (AO-SiC). The incorporation of nitrogen significantly enhances densification by increasing liquid phase viscosity, thereby suppressing additive evaporation and enabling >99.5 % relative density. Multi-cation doping (Y, Ce, Mg, Al) into the Y 2 Si 2 O 7 intergranular phase reduces eutectic temperature and promotes homogeneous sintering. Under irradiation to 7–8 dpa at 550–750 °C, both systems exhibit exceptional stability, attributed to the highly ionic Y 2 Si 2 O 7 structure resisting amorphization and accommodating dopants without segregation. Damage remains dominated by intragranular defect evolution in SiC grains, while AN-SiC demonstrates reduced radiation hardening and enhanced modulus recovery, highlighting the synergistic role of nitrogen in improving sintering and radiation resistance for Gen-IV reactor applications.