Enhancement of mechanical properties of SiC layer in TRISO particles via current‐induced stacking faults

Abstract Fully ceramic microencapsulated (FCM) fuel, as a key category of accident‐tolerant fuel, relies critically on the mechanical integrity of the silicon carbide (SiC) layer with the tristructural‐isotropic (TRISO) fuel particles for its service reliability. The introduction of stacking faults (SFs) in SiC has been demonstrated to significantly enhance its mechanical performance. Building on this principle, we propose an innovative flash spark plasma heat treatment strategy that tailors electrical parameters to induce the formation of SFs within the SiC layer. A modified spark plasma sintering system, equipped with a boron nitride‐insulated graphite mold, enabled direct current flow through TRISO particles, allowing thermal processing under varied power conditions. Under low‐voltage (3.46 V) and moderate‐current conditions, the SiC layer exhibited substantial improvements in mechanical properties, with nanohardness and elastic modulus reaching 35.3 and 328.6 GPa, corresponding to increases of approximately 50.2% and 43.6%, respectively, relative to the as‐deposited state. This remarkable strengthening effect arises from current‐induced high‐density SFs and Lomer–Cottrell lock networks, which effectively impede dislocation motion and enhance mechanical stability. This work elucidates the microstructural and mechanical evolution of the SiC under current‐assisted conditions, establishing a new paradigm for current‐mediated property tuning in ceramics and providing theoretical and practical guidance for designing a strengthened SiC layer in FCM fuels.