The presence of grown-in twins in nanocrystalline samples was found to enhance plastic deformation via twin-migration in which partial dislocations, emitted at the intersection of the twin boundary with the grain boundary, travelled through the entire grain. In samples without grown-in twins, full dislocation activity was observed to be the predominant slip mechanism. The results were explained in terms of generalized planar fault energy curves for the Al potential used. Simulations of 2-dimensional columnar nanocrystalline networks were also carried out in order to investigate the effect of the grain, and grain-boundary network, dimensions upon the mechanical properties of nanocrystalline systems.

The Influence of Twins on the Mechanical Properties of nc-Al. A.Frøseth, H.Van Swygenhoven, P.M.Derlet: Acta Materialia, 2004, 52[8], 2259-68