Effects of carbon nanomaterials on interfacial structure and mechanical properties of high temperature Ti matrix composites

TiC is widely used as an ideal reinforcement to strengthen titanium matrix composites (TMCs). The morphology, size and distribution of TiC and the interfacial structure of TiC-Ti are crucial to obtain good mechanical properties of titanium matrix composites. These are keys to achieve superior strength and good ductility in titanium matrix composites. Hence, we investigated the effects of TiC generated in situ from different carbon sources (i.e., amorphous carbon nanoparticles, reduced graphene oxide and graphene nanoparticles) on the interfacial structure and mechanical properties of Ti60 alloy. Amorphous carbon nanoparticles (ACNS), reduced graphene oxide (rGO) and graphene nanoparticles (GNPs) reinforced Ti60 composites were prepared using spark plasma sintering (SPS). Among the three carbon nanomaterials, ACNs and rGO reacted with Ti60 matrix to form TiC, facilitating interfacial bonding. GNPs were not completely reacted with Ti60 matrix and residual on the interface owing to its poor dispersion effect, resulting in interfacial structure defects. The mechanical properties of the ACNs/Ti60 and rGO/Ti60 composites are high than GNPs/Ti60 composites. The ultimate tensile strengths of ACNs/Ti60 composites were 1173.49 MPa, 702.96 MPa and 653.13 MPa at room temperature, 600 oC and 650 oC, respectively, improving by 17.63%, 14.13% and 16.21% over Ti60, respectively. The superior mechanical properties are attributed to the fact that ACNs and rGO are more easily dispersed in the Ti60 matrix. The reaction activity of ACNs and rGO are higher than GNPs, and more TiC phase content was formed after sintering. TiC formed a semi-coherent interface with the Ti60 matrix, promoting the interfacial bonding strength. It also played a role in grain refinement and load transfer effect. This work helps to further elucidate the reinforcement effect of TiC formed by different carbon nanomaterials on TMC.