Improving mechanical properties of Cu/CNTs composites by incorporating nanotwins

To exploit the combined strengthening effects of nanotwins and CNTs in Cu matrix composites, we successfully incorporated the nanotwins with a width ranging from ~3 nm to ~30 nm into the CNTs-reinforced Cu matrix composites using cryogenic rolling and optimizing the initial particle size of the raw Cu powders. The formation of nanotwins in the Cu matrix composite reinforced by only 0.2 wt.% CNTs is accompanied by the increased dislocation density and refined Cu grain size, resulting in much better strength-ductility synergy than the referenced composite without significant nanotwins formation. The strengthening and toughening mechanisms analysis demonstrates that the increased strength mainly derives from grain refinement strengthening, dislocation strengthening, and nanotwin strengthening. The strength improvement from the contribution of the nanotwins accounts for 19.9% of the overall increased strength for the composite. Meanwhile, the retainment of good tensile ductility can be reasonably explained by the increased dislocation accommodation ability contributed by the formed nanotwins and lower induced dislocation proliferation.