Interfacial microstructure of graphite flake reinforced aluminum matrix composites fabricated via hot pressing

The microstructure of graphite flake (GF) reinforced aluminum (Al) matrix (Al-GF) composites was observed in detail. Due to thermal mismatch between Al and GF, an inner structure of GF was damaged in proximity to the Al/GF interface, while the unique bridging of the sticky graphite sheets barely connected the Al matrix and GF. This result suggests that the GF interlaminar strength is weaker than the Al/GF interfacial strength; the GF interlaminar strength is thus the dominant determinant of the thermomechanical and mechanical properties of the Al-GF composite. Whereas the thermal conductivity of the Al-GF composite was consistent with that theoretically predicted, the outstanding thermal expansion coefficient (TEC) of the graphite was not reflected in the produced Al-GF composites. The damaged inner structure of GF in proximity to the Al/GF interface contributes to heat transfer but does not bear the load resulting from thermal stress.