GNP-Reinforced Al2024 Composite Fabricated through Powder Semi-Solid Processing

Abstract

In order to significantly enhance the performance of graphene in metal matrix composites, and avoid the interface reaction via the common method, the powder semi-solid processing (PSSP) technique was successfully used to fabricate a graphene nanoplatelet (GNP)-reinforced Al2024 composite. The blended powders of Al2024 and GNPs were cold-compacted after ball milling and then hot compressed at a semi-solid temperature, and no further hardening was performed. The GNPs were observed to change during the ball milling process, and a uniform dispersion of GNPs in the aluminum (Al) matrix composite was achieved. The microstructure and mechanical properties of the composites were evaluated, and fracture surfaces of the composites were analyzed to investigate changes in performance. Results showed that GNPs have effective interface with the Al matrix, and that Al₄C₃ was absent. GNP/Al2024 composites showed significant improvement in strength and favorable ductility. Additionally, the supreme tensile strength of the GNP/Al2024 composite could increase to approximately 524 MPa with 1.0 wt% of GNPs, which is about 41.6% higher than that of the Al matrix composite. The effect of GNPs on the mechanical properties of the composites was discussed.

Fig. 10 Tensile fractographs of GNP/Al2024 composites with different GNP content: (a) 0%; (b) 0.5%; (c) 0.8%; (d) 1.0%; (e) 1.5%; (f) high magnification of (e). White arrow-dimple; red circle-tear ridges; purple flash-GNPs.