Microstructure evolution and mechanical properties of copper coated graphene nanoflakes/pure titanium matrix composites

In this paper, a new electroless plating method to prepare copper @ graphene nanoflakes (Cu@GNFs) powders with different content of GNFs was developed. Then, the short-term ball milling and spark plasma sintering (SPS) were used to fabricate Cu@GNFs/Ti composites. The electroless copper plating method effectively improves the dispersion of GNFs and relieve the severe interfacial reaction between GNFs and Ti. Microstructures and the morphology of the mixed powders and the composites were characterized by the scanning electron microscopy (SEM), Raman spectroscopy, X-Ray diffraction (XRD), and transmission electron microscopy (TEM). The micro-hardness and compressive properties were measured for evaluating Cu@GNFs/Ti composites. Results showed that the yield strength and microhardness of the composites enhanced gradually with the increase of the GNFs content. The compressive yield strength of the 0.5 wt% Cu@GNFs/Ti composite reaches 693 MPa, which is increased by 179% compared with that of pure Ti (248 MPa). The high ductility of 50% was maintained. At the same time, the 0.5 wt% Cu@GNFs/Ti composite has a microhardness value of 281 HV, 97% higher than that of pure Ti (142 HV). Furthermore, the strengthening mechanism of mechanical properties of composites was discussed.