Nucleation of deformation twins in nanocrystalline face-centered-cubic metals processed by severe plastic deformation

摘要: Nanocrystalline (nc) materials are known to deform via mechanisms not accessible their coarse-grained counterparts. For example, deformation twins and partial dislocations emitted from grain boundaries have been observed in nc Al Cu synthesized by severe plastic (SPD). This paper further develops an earlier dislocation-based model on the nucleation of face-centered-cubic (fcc) metals. It is found that there exists optimum grain-size range which nucleate most readily. The critical twinning stress determined primarily stacking fault energy while size largely ratio shear modulus energy. formulated herein applicable fcc nanomaterials SPD techniques provide a lower bound twining stress.