It was demonstrated here that a large fraction of high-angle grain boundaries, and a low dislocation density, could significantly improve the toughness and uniform elongation of ultra-fine grained Cu by increasing the strain-hardening rate without any concomitant sacrifice in yield strength. The results provided a strategy for synthesizing tough ultra-fine grained materials.

Tougher Ultrafine Grain Cu via High-Angle Grain Boundaries and Low Dislocation Density. Y.H.Zhao, J.F.Bingert, Y.T.Zhu, X.Z.Liao, R.Z.Valiev, Z.Horita, T.G.Langdon, Y.Z.Zhou, E.J.Lavernia: Applied Physics Letters, 2008, 92[8], 081903