Fig. 5: Typical microstructures and performance.

a EBSD micrographs of hot-rolled 3D-GLNN/Cu from three orthogonal directions. Scale bar, 5 μm. b Bright-field TEM image of the 3D-GLNN/Cu composites. Scale bar, 500 nm. c, d Bright-field scanning transmission electron microscope (STEM) image of the 3D-GLNN/Cu composites (c) and the corresponding HRTEM image taken near the grain boundaries of the composite (d). Scale bar, 200 nm (c); 5 nm (d). e Tensile stress-strain curves of pure Cu, RGO/Cu, and 3D-GLNN/Cu. f Comparative bar chart of mechanical properties of pure Cu, RGO/Cu, and 3D-GLNN/Cu. g Retention of fractural elongation versus strengthening efficiency of tensile strength plot, showing that the as-prepared 3D-GLNN/Cu composite had an outstanding combination of strengthening efficiency and ductility. h The in-plane thermal conductivities of pure Cu, RGO/Cu, and 3D-GLNN/Cu. i Comparative bar chart of thermal conductivities of pure Cu, RGO/Cu, and 3D-GLNN/Cu at room temperature (25 °C) and 300 °C. j TC enhancement efficiency versus graphene content plot, demonstrating a high enhancement efficiency of 3D-GLNN in thermal conductivity at a relatively small graphene content compared with other reported nanocarbon reinforced Cu matrix composites. Inset is the illustration of the electrons and phonons transfer channels in 3D-GLNN and the reduction of electrons scattering in the Cu matrix near the interface.