▎ 摘　　要

Owing to the high strength of copper (Cu) and high in-plane thermal conductivity (K-T) of graphene (Gr), Gr/Cu composites are increasingly demanded as the advanced thermal management materials to ensure the heat dissipation. The heat transport performance is primarily influenced by two aspects: (1) Intrinsic parameters of Gr, including its crystallinity, layer number (N), coverage and spatial distribution and (2) Gr/Cu interface related properties, such as interface bonding, residual strain and defects near the interface. In this work, by combining roll-to-roll (R2R) chemical vapor deposition (CVD) and subsequent hot isostatic pressing (HIP) techniques, highly paralleled Gr reinforced Cu matrix composites with controllable N were fabricated. Experimental results show that similar to 5-6L Gr/Cu composites manifest the highest degree of anisotropy, including (1) the highest K-r (394 +/- 5 W/mK, similar to 22% higher than pure Cu counterpart), and (2) the lowest through-plane thermal conductivity (K-z) (257 +/- 4 W/mK, similar to 25% lower than pure Cu counterpart). When N varies from 1 to 5, the continuously increased K-r and decreased K-z are majority influenced by intrinsic properties of Gr, which is also validated by multiscale simulations and time-domain thermoreflectance analysis. When N increases to similar to 10, both K-r and K-z exhibit opposite trend, that may attribute to the reduced Gr coverage and large volume fraction of amorphous carbon. Moreover, the residual strain and defects at the interface could lower both K-r and K-z as well. This study suggests that advanced synthesis of high-crystallinity thick Gr may be promising to obtain superb K-r in Cu matrix composites. (c) 2020 Published by Elsevier Ltd on behalf of Acta Materialia Inc.