EDM-induced micro/nano-array surface engineering enabling ultrahigh thermal conductivity and excellent mechanical reliability in of Cf/C composite/Haynes 230 alloy dissimilar brazed joints

: Heterogeneous joining between C f /C composite and Haynes 230 superalloys is critical for aerospace thermal management yet severely limited by interfacial thermal resistance and mechanical reliability. Here we report a one-step EDM surface engineering strategy to construct controllable micro/nano groove arrays on C f /C composite, which simultaneously enhances mechanical interlocking, chemical bonding, and multidimensional heat transfer pathways. The optimized joint (250 μm interval, 90 μm depth) achieves a thermal conductivity of 42.3–46.6 W·m -1 ·K -1 and thermal resistance as low as 1.59 cm 2 ·K·W -1 , with a shear strength of 25.4 MPa. After 200 h thermal cycling (600–900 °C), the joint retains excellent thermomechanical stability without obvious performance degradation. Mechanism analysis reveals that the macroscopic area expansion and microscopic metal–carbon fiber core–shell thermal bridges synergistically break the thermal barrier at dissimilar interfaces. This study not only provides a scalable solution to the thermomechanical trade-off challenge at heterogeneous material interfaces, but also lays a new methodological foundation for the reliable integration of high-power thermal management components.