The grain-boundary structures of ultrafine-grained pure Cu, fabricated by means of accumulative roll bonding, were studied. The atomic structures of grain boundaries in the accumulative roll-bonded Cu were observed by means of high-resolution electron microscopy. In order to compare the grain boundaries in accumulative roll-bonded Cu with equilibrium grain boundaries, the grain-boundary energy and structure of symmetrical tilt boundaries with a <110> common axis in pure Cu were computed by molecular dynamics simulation. The low-angle boundaries in the accumulative roll-bonded Cu were basically described by a conventional dislocation model, while simultaneously there were local structures having high-energy configurations. Grain boundaries with large misorientations, in the accumulative roll-bonded Cu, were basically described by the structural units predicted for normal grain boundaries by molecular dynamics. The present results indicated that the atomic structures of the boundaries in Cu severely deformed by the accumulative roll bonding were rather similar to those of the equilibrium grain boundaries; except for local distortions.

Grain Boundary Structure of Ultrafine Grained Pure Copper Fabricated by Accumulative Roll Bonding. K.Ikeda, K.Yamada, N.Takata, F.Yoshida, H.Nakashima, N.Tsuji: Materials Transactions, 2008, 49[1], 24-30