Tailoring interface structure and enhancing thermal conductivity of Cu/diamond composites by alloying boron to the Cu matrix

Diamond particles reinforced Cu matrix (Cu/diamond) composites were prepared by alloying 0.1-1.0 wt% B to the Cu matrix in order to tailor the interface structure. The interface structure evolves from discrete triangular carbides into continuous jig-saw carbides depending on the availability of boron source in the Cu-B matrix. We report the highest thermal conductivity of 868 W/mK so far in boron-modified Cu/diamond composites, which originates from the discontinuous carbide interface in the Cu-B/diamond composites. The parallel connection of interfacial thermal resistances of the discontinuous carbide interface reduces the total interfacial thermal resistance and therefore promotes phonon transfer across the Cu/diamond interface. We clarify the formation mechanism of discontinuous carbide interface in the Cu-B/diamond composites and demonstrate the decisive role of discrete triangular carbides in enhancing thermal conductivity of Cu/diamond composites. The results help to establish the method of metal matrix alloying to prepare Cu/diamond composites with high thermal conductivity for thermal management applications.