Tailoring the composite interface at lower temperature by the nanoscale interfacial active layer formed in cold sprayed cBN/NiCrAl nanocomposite

Strong interfacial bonding is usually preferred in composite materials to obtain enhanced heat, electron transport and load transfer abilities. To induce chemical interfacial bonding in cubic Boron Nitride (c-BN) based composites, ultra-high temperatures (1200–2000 °C) and pressures (7–12 GPa) are required in conventional sintering due to the high chemical inertness of c-BN. In this work, a nanometer thick active layer containing a high concentration of crystal defects including lattice disorder, dislocations, and grain boundaries is formed at the reinforcement/matrix interface region in cubic BN/NiCrAl composite during supersonic impact consolidation. Kinetics and thermodynamics of the interfacial reaction are greatly enhanced by the active layer, so that a c-BN/Cr₂N/AlB₂/NiCrAl interfacial structure was formed at a low annealing temperature of 825 °C. Due to the limited thickness of the active layer, the interfacial reacting products were confined to tens of nanometers width and excessive interfacial reaction induced mechanical property deterioration is avoided. The enhanced interfacial bonding leads to a substantial improvement in thermal conductivity, from 15.4 to 36.5 W m^{− 1} K^{− 1}.