A new process, Repetitive Corrugation and Straightening (RCS), has been developed to create bulk, nanostructured copper. In this investigation, a high purity (99.99 percent) copper bar measuring 6 X 6 X 50 mm with an average grain size of 765 #mu#m was used as the starting material. It was repetitively corrugated and straightened for 14 times with 90 deg rotations along its longitudinal axis between consecutive corrugation-straightening cycles. The copper was cooled to below room temperature before each RCS cycle. The grain size obtained after the RCS process was in the range of twenty to a few hundred nanometers, and microhardness was increased by 100 percent. Both equilibrium and non-equilibrium grain boundaries are observed. This work demonstrates the capability of the RCS process in refining grain size of metal materials. The RCS process can be easily adapted to large-scale industrial production and has the potential to pave the way to large-scale structural applications of nanostructured materials.
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