Fabrication of bulk aluminum-graphene nanocomposite through friction stir alloying

Friction stir alloying is primarily employed for the fabrication of surface composite to improve surface properties like hardness, wear resistance, and corrosion resistance without significantly affecting the bulk properties of the alloy. The present study demonstrates the novel method for the fabrication of bulk aluminum-graphene nanoplatelets composite by using friction stir alloying. Here, the novelty is shown through the method of graphene nanoplatelets incorporation in the stir zone. For this purpose, a channel is fabricated on the cross-sectional surface of the aluminum plate and filled with graphene nanoplatelets. It is then covered by the cross-sectional surface of another aluminum plate of same dimensions and friction stir alloying is carried out. Reference material (RM) is also fabricated at the same parameters without any graphene nanoplatelet reinforcements for the performance evaluation of the nanocomposite. The microhardness of the fabricated composite increased by ∼57% as compared to the reference material. However, the tensile strength of the fabricated Al-graphene nanoplatelet composites decreased marginally as compared to reference material. The strengthening of the composite is explained systematically by various mechanisms. The results of microhardness and tensile test were corroborated with various characterization methods such as optical micrographs, scanning electron microscopy, atomic force microscope, and X-ray diffraction.