Synergistically enhancing strength, toughness and electrical conductivity of CNTs-Mo/Cu composite by constructing network architecture

To achieve the optimal trade-off among strength, toughness and electrical conductivity, the CNTs-Mo/Cu composites with different architectural structures were fabricated by the combination of wet mixing, ball milling, spark plasma sintering (SPS) and hot rolling. The microstructure, mechanical properties and electrical conductivity of the CNTs-Mo/Cu composites were investigated, and the strengthening and toughening mechanisms were also explored based on the experimental results along with finite element simulation and first-principles. It is found that CNTs-Mo exhibits a dispersed distribution in the Cu matrix for the 0.05 wt%CNTs-Mo/Cu composite, whereas a discontinuous network structure occurs in the 0.10 wt%CNTs-Mo/Cu composite. At 0.15 wt%CNTs-Mo, the complete continuous network architecture presents in the 0.15 wt%CNTs-Mo/Cu composite. Moreover, the Mo 2 C modified on the surface of CNTs forms a semi-coherent interface with Cu, which facilitates the enhancement on the interfacial bonding between CNTs and Cu. The 0.15 wt%CNTs-Mo/Cu composite with continuous network structure displays the maximum tensile strength of 455.1 MPa, the largest elongation of 39.1 % and the optimum fracture toughness of 22.4 MPa m 1/2 , while an excellent electrical conductivity of 93.2 %IACS can also be achieved simultaneously. Furthermore, the finite element simulations reveals that the network structure suppresses stress concentration and hinders crack propagation, thereby promoting load transfer. The first-principles calculation demonstrates that Cu-Mo 2 C and Mo 2 C-CNT heterostructures display the higher absolute value of binding energy and more obvious charge transfer than the CNT-Cu heterostructure, suggesting that the incorporation of Mo 2 C plays a crucial role in improving the interfacial stability and interfacial bonding strength of CNTs-Cu. The simultaneous improvement on strength and toughness of the 0.15 wt%CNTs-Mo/Cu composite can be attributed to strong interfacial bonding, effective load transfer, as well as crack deflection and bridging effects stemmed from the CNTs.