Microstructure and mechanical properties of graphene nanoplatelets reinforced Al matrix composites fabricated by spark plasma sintering

Abstract

Abstract Graphene nanoplatelets reinforced aluminum matrix (GNPs/Al) composites were successfully fabricated by high-energy ball milling and spark plasma sintering. The microstructure and mechanical properties of the GNPs/Al composites were investigated. Microstructure and distribution of GNPs were analyzed with a scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). Tensile properties and hardness were studied at room temperature. The GNPs/Al composites with the well-dispersed GNPs and good densification were fabricated, indicating this technology can effectively fabricate the GNPs/Al composites. The randomly distributed nano-rods Al4C3 was found in the GNPs/Al composites fabricated at 600 °C. The ultimate tensile strength, yield strength, elongation, as well as Vickers hardness of GNPs/Al composites increase with the increase of fabrication temperature. The GNPs/Al composites with nano-Al4C3 have a good balance between tensile strength and elongation, because the nano-sized Al4C3 phase helps to improve the interfacial bonding and mechanical properties of GNPs/Al composites. The GNPs/Al composites exhibit a ductile mode of failure, and GNPs pull-out was detected at the fracture surface. The strengthening mechanism of GNPs/Al composites was discussed according to the load transfer strengthening, Orowan strengthening and dislocations strengthening, and the interfacial Al4C3 phase plays a critical role in determining the load transfer efficiency of GNPs. This paper may render significant information for understanding the strengthening behaviors of GNPs reinforced metal matrix composites.