Synthesis and mechanical properties of Al matrix composites reinforced with few-layer graphene and graphene oxide

The reinforcing effect of graphene nanosheets in Al matrix composites has been studied. The Al powder was mixed with 1 wt% of few-layer graphene (FLG) and graphene oxide (FLGO) using a wet method followed by cold-compaction and sintering. SEM, OM, FTIR, and Raman spectroscopy were used for characterization of the samples and inspection of the reactions occurred during the synthesis of composites. Mechanical properties of the samples were studied using compression and hardness tests. The analyses indicated that FLGO was reduced during the wet mixing of gas-atomized Al-FLGO composite powder and covered the surfaces of Al powder particles, giving rise to 54% and 28% enhancement in the compressive yield strength and hardness of the monolithic Al, respectively. Mechanical milling of the Al powder increased the reduction degree of FLGO and thus, significantly enhancing the hardness (105%) and compressive yield strength (85%) of the Al. A higher degree of densification was achieved for FLG˗reinforced Al matrix composites in comparision to Al/FLGO composites. The utilized synthesis method is a simple and fast process which can be considered as a promising alternative for the synthesis of other graphene-reinforced metal matrix composites with improved mechanical properties.