Effect of Ti interlayer on interfacial thermal conductance between Cu and diamond

Cu/Ti bilayers were magnetron sputtered onto a diamond substrate to simulate interfaces in diamond particles reinforced Cu matrix (Cu/diamond) composites. The Cu/Ti/diamond system was tuned to Cu/Ti/TiC/diamond and Cu/TiC/diamond structures by annealing the Ti interlayer at 1073 K. The interfacial thermal conductance (G) between Cu and diamond was experimentally measured by a time-domain thermoreflectance (TDTR) technique to investigate the dependence of the G on the Cu/interlayer/diamond structure. The Cu/TiC/diamond structure exhibits higher G of 76 MW m(-2)K(-1) than the Cu/Ti/TiC/diamond of 60 MW m(-2) K-1, the Cu/Ti/diamond of 30 MW m(-2) K-1, the as-deposited Cu/diamond of 66 MW M-2 K-1, and the annealed Cu/diamond of <1 MW m(-2) K-1. The measured G values are in broad agreement with the calculated values using an acoustic mismatch model (AMM). The results show that interfacial bonding is more critical than vibrational match of phonons in increasing the G between Cu and diamond as well as the thermal conductivity of Cu/diamond composites. A promising interlayer configuration is obtained as Cu/TiC/diamond, which provides an idea for design and preparation of high thermal conductivity Cu/diamond composites. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.