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

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 degrees 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. (C) 2020 Elsevier B.V. All rights reserved.