Effect of flake powder metallurgy on thermal conductivity of graphite flakes reinforced aluminum matrix composites

The optimization of metal–matrix composite material is linked firstly with the intrinsic properties of the matrix and the reinforcement used and secondly with the reinforcement–matrix interfacial zone and the distribution/orientation of the reinforcement inside the metal–matrix. Flake powder metallurgy was used to fabricate graphite flake reinforced aluminum matrix (Al/GF) composites fabricated by vacuum hot pressing. Two types of aluminum powders morphology were used: spherical (Al_S) and flake (Al_F) powders. A higher thermal conductivity in the in-plane direction of the graphite flakes was obtained for Al/GF composite materials fabricated with aluminum flake powder. In addition to a better orientation of the GF in the flake aluminum matrix, a 3D puckered surface and plane surface are formed at the Al/GF interface in, respectively, Al_S/GF and Al_F/GF composite materials. Due to the morphology incompatibility between the graphite flakes and the spherical powder, the damaged inner structure of GF contributes to a limited enhancement of thermal conductivity in Al_S/GF composite materials.