Tailoring nano-carbon/IN718 interfaces via specific surface areas for the synergistic control of thermal expansion and conductivity

Inconel 718 (IN718) is widely used in high-temperature applications but is limited by low thermal conductivity (TC) and high thermal expansion coefficient (CTE). Here, we report an interface-engineering strategy for IN718 composites using nano-carbon reinforcements with different specific surface areas. One-dimensional carbon nanotubes and two-dimensional reduced graphene oxide (rGO) were incorporated via ball milling. The high specific surface area of rGO promotes extensive interfacial carbide formation (e.g. NbC), enabling enhanced phonon transport and suppressed matrix expansion. Consequently, the IN718-rGO composite achieves TC of 14.31 W/m·K and a reduced CTE of 11.2 µm/m·K, outperforming both monolithic IN718 and CNT-reinforced composites.