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The present research was motivated by two unsettled questions. First, what are the detailed characteristics of the nanostructured interface in a nano-carbon/metal composite containing interfacial reaction products? Second, what other factors in interfacial carbide (not only its content) can influence the interface strength and mechanical properties, and if it is true? We developed a novel strategy to uncover these issues in graphite nano-flakes (GNFs)/Ti composites. Four GNFs/Ti samples with similar concentration of interfacial carbides were prepared under the guidance of DICTRA simulation. High-resolution transmission electron microscopy and precession assisted electron diffraction were applied to gain fundamental insight into the mechanisms that affect the characteristics of GNFs/Ti interfaces. The tensile results showed that the interfacial morphologies, GNFs-TiC x bonding strength, preferred orientation and growth defects were significant factors that were closely associated with the mesoscopic mechanical behavior. Interestingly, the heat-treated (HT) 1123K-600s GNFs/Ti composite exhibited the optimal tensile properties and superior GNFs-TiC x "synergetic" effect. The origin of such findings were explored from the viewpoint of nano-cracks/dislocation-interface interaction. This work provides a new insight in understanding the interfacial characteristics of GNFs/Ti composite, and underscores the importance of reaction interface design in strengthening of bulk GNFs/metal composite. Image 1 [ABSTRACT FROM AUTHOR]

An increasing number of reports have demonstrated enormous strength enhancements in titanium matrix composites (TiMCs) reinforced with graphene nanoflakes (GNFs) on account of the superior mechanical properties of GNFs. Unfortunately, the difficulty of uniform dispersion and severe interfacial reaction are simultaneously the most challenging and serious issues in GNFs reinforced TiMCs. In this work, we applied electroless plating method to prepare Ni decorated GNFs (Ni-GNFs) as a reinforcement in Ti matrix to uniformly disperse the GNFs in Ti matrix and relieve the severe interfacial reaction between metal and carbon nanophase. The composite reinforced by low content Ni-GNFs (0.05 wt%GNFs) exhibiting ultimate strength of 793 MPa (+40% compared to monolithic pure Ti), have been processed by short time ball milling process followed by spark plasma sintering (SPS) and hot-rolling (HR). Enormous strength increase of the composite can be attributed to a homogeneous distribution of Ni-GNFs in the Ti matrix coupled with the formation of special interface (Ti/Ti 2 Ni/nano-TiC X /Ni-GNFs). The load transfer mechanism of Ni-GNFs in composites was investigated by in-situ tensile test, which shows the great interfacial load transfer capability. This work provides a new strategy for dispersion and interface analysis of GNFs reinforced Ti matrix composites. [ABSTRACT FROM AUTHOR]