Mechanical properties and rolling behaviors of nano-grained copper with embedded nano-twin bundles

By means of dynamic plastic deformation (DPD) at liquid nitrogen temperature (LNT), bulk nano-grained copper samples with embedded nano-twin bundles were prepared. Subsequent cold rolling (CR) of the LNT-DPD Cu led to a reduction in quantity of 2 nano-twin bundles and a slight grain coarsening, accompanied by a decrease in grain boundary (GB) energy from 0.34 to 0.22 J m(-2). increasing CR strain leads to a saturation grain size of similar to 110 nm, which is less than half of that in the severely deformed Cu from the coarse-grained form. Decreased strength and enhanced ductility were induced by CR in the LNT-DPD sample. The saturation yield strength in the LNT-DPD Cu during CR was similar to 105 MPa higher than that in conventional severely deformed Cu, which originates from the finer grains as well as the nano-scale twins in the LNT-DPD sample. The enhanced ductility is primarily attributed to CR induced GB relaxation. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.