Ultra-fast joining of SiC_f/SiC composites via joule-heated carbon fiber network with Ti–C–mediated Ni suppression

The reaction between SiC and Ni-based filler metals produces brittle Ni–Si compounds, severely degrading joint mechanical performance. This study proposes an ultra-fast Joule heating strategy for joining SiC_f/SiC composites using TiNiNb filler metals, where a 3D carbon fiber network serves as both an integrated heating source and reinforcing phase, completing the entire process within 50 s with a heating rate of 700 °C/s. DFT calculations and experimental analyses reveal that electron transfer from Ti atoms to carbon enables rapid TiC nucleation at the interface, kinetically suppressing Ni diffusion and subsequent brittle Ni–Si formation. Molecular dynamics (MD) simulations further reveal that the Ti–C–mediated interface significantly augments the intrinsic bonding energy and promotes a more uniform dislocation distribution. The 3D carbon fiber network serves as a stress-buffering layer, redistributing interfacial stress to alleviate thermal expansion mismatch between SiC_f/SiC and the filler metal. This approach yields joints with a shear strength of 39.05 MPa, representing a 121.7% enhancement compared to conventional furnace brazing, offering a promising pathway for the reliable joining of aerospace hot-end components under extreme conditions.