Deformation mechanism analysis of fcc metals by GPF

The second nearest-neighbor modified embedded atom method (2NN-MEAM) is used to calculate the generalized planar fault (GPF) energies of the fcc metals Al, Ni and Cu. In this method, the twinning tendency is consistent in the criteria of the γsf and γusf/γutf values, that is, deformation twinning is most preferable in Cu and rarely seen in Al. While full dislocation is easy to be observed in Al for its lowest γsf/γusf and highest γusf/γutf values. Even in nanomaterials, the relatively low γusf/γutf value can be the reason for a more rigorous condition in Al to create a twin than Cu, which is also evidenced in experiments. The GPF energy increases with vertical expansion and the magnitude of the increase is determined by Young's modulus of the metal to a certain extent.