A brazed thermal bridge of continuous Mo-network for extreme heat transfer between C_f/C composite to Haynes 230 alloy

The pursuit of efficient thermal management under extreme environments—as encountered in thermonuclear fusion reactors—is fundamentally hampered by the formidable challenge of creating robust and conductive joints between dissimilar high-temperature materials, such as C_f/C composite and Haynes 230 alloy. Here, we devise a multi-layered Mo-Cu/Cu/Ti (MCT) filler that, upon brazing, in-situ constructs a continuous, three-dimensional molybdenum network within the joint. It serves as a dedicated thermal superhighway, effectively bypassing the intrinsic phonon-scattering interfaces that typically plague conventional brazing seam. The resulting joint exhibits an exceptional thermal conductivity of 36.1–40.7 W m⁻¹ K⁻¹ and a low overall thermal resistance below 1.8 cm² K W⁻¹ in the 600–900 °C range. Concurrently, the joint maintains a shear strength of >9 MPa even at the upper service temperature of 900 °C. Crucially, the joint survives 100 aggressive thermal cycles (200 h) between 600 and 900 °C with negligible degradation in both thermal and mechanical properties, demonstrating unparalleled reliability for long-term service. In a practical demonstration under a high heat flux of 2.7 W mm⁻², the brazed assembly enhances the surface temperature by 13 °C relative to a non-joined interface, unequivocally validating its superior heat-transfer capability in a simulated service scenario. This work provides a viable strategy for thermal management in fusion reactors and aerospace thermal protection systems, overcoming the temperature limitations of conventional thermal interface materials.