Uniform dispersion of multi-layer graphene reinforced pure titanium matrix composites via flake powder metallurgy

In this study, a micro-laminated structure of titanium matrix composite with uniformly dowel-like and aligned multi-layer graphene (MLG) was fabricated by flake powder metallurgy. Flake ball milling method was applied to efficiently obtain flaky Ti powder with embedded MLGs flakes. Spark plasma sintering (SPS) was applied to consolidate mixed powders, in order to obtain the laminated billet which can enable the MLGs to preserve its original structure. Subsequent hot-rolling (HR) was applied to form the tight interface and reduce the internal defection of composites. Results showed that the composites interface owns in-situ formed TiC layer between MLGs and matrix. Also, the composites with micro-laminated structure showed significant improvement of strength. Consequently, a uniform disperse of MLG enabled the as-designed composites to exhibit 280% increase in yield strength (similar to 2 GPa), 96% increase in nano-hardness and 16% increase in elastic modulus as compared to monolithic flake pure Ti (HR normal direction (ND)). The micro-laminated structure and well-dispersed MLGs were believed to be beneficial to harden and strengthen Ti matrix, and the relevant strengthening mechanisms of the composites were carefully discussed.