Grown-in twin boundaries affecting deformation mechanisms in nc-metals

Molecular dynamics simulations have recently shown that the presence of grown-in twin boundaries in nc-Al promotes slip activity in the form of twin boundary migration. In this letter we investigate the effect of grown-in twin boundaries on the plastic deformation mechanism in nc-Ni and Cu, and show that (1) for these particular fcc metals twin boundary migration is not the favored deformation mechanism and (2) that the Schmid factors of the grown-in twin plane play a correspondingly important role. The results are explained in terms of the different ratios of the extrema of the generalized planar fault curves.