On the geometry of twin boundaries and their contribution to the strengthening and recovery of FCC polycrystals

Results are presented of a comprehensive study of: (a) the 3-dimensional geometry of twin grains in FCC polycrystals; (b) the strengthening effect of twin boundaries (TBs); and (c) their role in the process of recovery. Two types of twin shapes were observed: lamellar and edge. The relative number of twins of a given shape depends on the stacking fault energy of the material. It is shown that TBs in the early stages of plastic deformation significantly strengthen FCC polycrystals. They also significantly contribute to the process of recovery of pre-strained polycrystals.