High strength-high conductivity carbon nanotube-copper wires with bimodal grain size distribution by spark plasma sintering and wire-drawing

Copper and 1 vol% carbon nanotube-copper cylinderswith a micrometric copper grain size and either a unimodal or a bimodal grain size distribution were prepared using spark plasma sintering. The cylinders served as starting materials for room temperature wire-drawing, enabling the preparation of conducting wires with ultrafine grains. The tensile strength for the carbon nanotube-copperwires is higher than for the corresponding pure copper wires. We show that the bimodal grain size distribution favors strengthening while limiting the increase in electrical resistivity of the wires, both for pure copper and for the composites.