Interface evolution and its influence on mechanical properties of CNTs/Cu-Ti composite

Carbon Nanotubes (CNTs)/Cu-Ti composites with strong interfacial bonding were successfully prepared by Molecular Level Mixing (MLM) combined with Spark Plasma Sintering (SPS) method. The relationship between interface evolution and mechanical properties was carefully investigated by High Resolution Transmission Electron Microscopy (HRTEM). It was found that three typical transition interfaces (Ti8C5, Ti8C5 + TiC, TiC) were formed between the CNTs and the Cu-Ti matrix when 0.3 wt% CNTs/Cu-Ti composite powder was sintered at 1073 K for 10min, 20min and 30min respectively. Strong interfacial bonding and well-preserved CNTs structure were simultaneously realized in the sample which was sintered at 1073 K for 10min. The interface evolution phenomenon of the Ti8C5 to the TiC interface transition phase and a parallel orientation relationship ((219)(Ti8C5)//(111)(TiC)) were observed under a sintering time of 20 min at 1073 K. The 0.3 wt% CNTs/Cu-Ti composites sintered at 1073 K for 10 min exhibited yield strength of 368 MPa and tensile strength of 512 MPa, which were 59% and 51% higher than that of unreinforced Cu-Ti, 27% and 25% higher than that of 0.3 wt% CNTs/Cu composites without alloying. This study provides some new insights into the interfacial regulation of the CNTs/Cu composites with strong interfacial bonding and reinforcing effects.