Towards high performance in Ti-based composite through manipulating nickel coatings on graphene reinforcement

Graphene nanoflakes (GNFs) surface metallization is a potential method to simultaneously achieve homogeneous GNFs dispersion and suitable interfacial bonding in metal matrix composites (MMCs). In this study, the effect of nickel coating microstructure of GNFs on strengthening titanium matrix composites (TMCs) was investigated. To this end, nickel-coated graphene nanoflakes (Ni-GNFs) with two different states were produced via electroless plating. The Ni-GNFs/Ti bulk composites were consolidated by combining short-time ball milling, spark plasma sintering (SPS) and hot rolling (HR). Results showed that the reinforcements were well dispersed in the Ni-GNFs/Ti composites coupled with remarkably strength improvement, which resulted from the precipitation of NiTi₂ intermetallic compound and strong interfacial bonding. The partially Ni-coated GNFs have a better strengthening effect than fully Ni-coated GNFs in TMCs, which was closely associated with the formation of a special interfacial microstructure. As a result, the composite with partially Ni-coated GNFs exhibited the highest tensile strength of 821 MPa, as well as excellent ductility (~18.3%). This finding may provide new strategies for the preparation of high-performance TMCs through interfacial microstructure design.