A combination of ball milling and high-ratio differential speed rolling for synthesizing carbon nanotube/copper composites

High-ratio differential speed rolling (HRDSR) was used to fabricate carbon nanotube (CNT)/Cu composites. The copper sheath containing the CNT/Cu composite powders, which were prepared by the high-energy ball-milling technique, was subjected to HRDSR. The large amount of redundant shear strain induced during HRDSR significantly enhanced the dispersion and directional alignment of the CNTs in the matrix and the effect of the addition of CNTs on grain-size reduction. In contrast, the clusters of CNTs in the ball-milled powders were poorly disintegrated and the CNTs were highly damaged when conventional rolling was used. As a result, HRDSR-processed Cu composites exhibited superior mechanical properties compared with their counterparts fabricated by conventional rolling.