Evolution of nano-grains in high purity copper by accumulative roll-bonding process

The evolution of nano-grains in oxygen free copper with accumulative roll-bonding is investigated by TEM and EBSD analysis. The ultrafine grains developed in the sample after 8-cycle ARB. It was found that the mean spacing of grain boundaries, which was 63 microm in initial material, reduced to 5.5 microm after 1 cycle, then surprisingly 450 nm after 3 cycles. In addition, the fraction of high-angle boundaries in the sample after 1-cycle ARB was 0.32, but it after 3-cycle ARB was surprisingly more than 0.6. Texture development of the ARB processed samples is different depending on the number of ARB cycles.