Mechanical and tribological properties of graphene nanoplatelets-reinforced titanium composites fabricated by powder metallurgy

Titanium matrix composite reinforced by graphene nanoplatelets (GNPs) was fabricated via powder metallurgy route. Hot isostatic pressing and hot extrusion were used to consolidate the mixed powder of GNPs and TC4 titanium (Ti) alloy. The microstructures, mechanical properties and sliding wear performance of Ti/GNPs composite had been researched to evaluate the reinforcing effect of GNPs on titanium matrix. Microstructure observation indicates that GNPs could restrain grain growth slightly in titanium matrix. Titanium matrix and graphene exhibit a clean and firm interface formed by means of metallurgical bonding on atomic scale. Compared with the monolithic titanium alloy, the composite with 1.2 vol.% GNPs exhibits significantly improved elastic modulus and strength. The sliding wear test shows that there is an obvious enhancement in the tribological performance of Ti/GNPs composite with 1.2 vol.% GNPs. The results of this work indicate that GNP is an efficient reinforcement material in titanium matrix. The strengthening mechanism including precipitates strengthening, load transfer and grain refinement mechanism of GNPs in titanium matrix was discussed. A modified shear-lag model was used to analyze the reinforcement contribution of the stress transfer mechanism. The calculation shows that the stress load mechanism constitutes the main strengthening mechanism in Ti/GNPs composite.