Preparation and tensile properties of homogeneously dispersed graphene reinforced aluminum matrix composites

It is important to achieve homogeneous distribution of graphene in aluminum matrix composites and meanwhile protect the structure of graphene. Graphene oxide (GO) sheets with the negative charge were prepared by a modified Hummers' method and Al powders were coated by hexadecyl trimethyl ammonium bromide (CTAB) to obtain the surface positive charge. Then, GO-Al powders were obtained by electrostatic self-assembly to realize the homogeneous adsorption of GO sheets on Al powders. Finally, graphene reinforced aluminum matrix composites (Gr/Al) were fabricated by powder metallurgy. Morphologies of GO sheets and GO-Al powders, microstructures and tensile fractographs of the composites were observed. The effect of graphene content on the tensile properties and fracture mechanisms of Gr/Al composite were also investigated. The results show that GO sheets are uniformly adsorbed on the surface of CTAB coated Al powders, which realizes the homogeneous dispersion of graphene in the Al matrix. With increasing the graphene contents, the ultimate tensile strength of the composites initially increases and later decreases. However, the elongation to fracture of the composite gradually decreases. The fracture mode of the Gr/Al composites changes from ductile fracture to brittle fracture with increasing the graphene contents. (C) 2016 Elsevier Ltd. All rights reserved.