The role of Cr interlayer in determining interfacial thermal conductance between Cu and diamond

•Cu/Cr bilayer films were deposited onto diamond to simulate actual interface in Cu/diamond composites.•The h between Cu and diamond was measured by a time-domain thermoreflectance technique.•The Cu/Cr/Cr3C2/diamond structure with a mixed Cr and Cr3C2 interlayer exhibits the maximum h value of 168 MW/m2 K.•This study provides guideline for interface modification to attain high thermal conductivity in Cu/diamond composites.