Effect of reinforcement content on microstructures and mechanical properties of graphene nanoflakes-reinforced titanium alloy matrix composites

In this study, we prepared nickel and phosphorus decorated graphene nanoflakes (Ni–P@GNFs) as a reinforcement in Ti–6Al–4V (TC4) alloy matrix by an electroless plating method. It can enhance the interface bonding force between GNFs and TC4 matrix, and facilitate uniform dispersion of the GNFs in the TC4 matrix. This in turn relieve severe interface reactions between the metal and the carbon nanomaterial. The Ni–P@GNFs/TC4 composites with different GNFs content (0, 0.25, 0.5, 0.75, 1, 1.5 wt.%) were fabricated via short-term ball milling and spark plasma sintering (SPS). The effects of reinforcement content on microstructures and mechanical properties of Ni–P@GNFs/TC4 composites were studied while the sintered composites were characterized by X-Ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the mechanical properties of Ni–P@GNFs/TC4 composites were dramatically improved due to the homogeneous dispersion of GNFs in the TC4 matrix. The compressive strength of 0.5 wt.% Ni–P@GNFs/TC4 composite reaches 1133 MPa: this was an increase of 30.6% versus TC4 (867 MPa) while maintaining 34.2% ductility. The strengthening mechanism of the mechanical properties of the composites are discussed.