Synergistic Strengthening of Dislocation and Heterodeformation Induced in Gradient Nanograined Copper Film: A Molecular Dynamics Study

Unlike conventional homogeneous nanograined (NG) materials, gradient structured materials combine high strength and ductility. The gradient nanograined (GNG) structures are divided into three zones by grain size: the small-grained zone, the transition-grained zone, and the large-grained zone. Molecular dynamics (MD) simulation is performed to investigate the effect of the widths of zones on the strength of GNG structures with different grain sizes. The simulation results reveal the strengthening mechanism of GNG structures from the perspective of microstructure evolution. With the change in grain size, the dominant deformation mode changes from grain boundary (GB) activities in the mall-grained zone to dislocation slip in the large one. The inverse Hall-Petch phenomenon is observed during plastic deformation. Synergistic strengthening of dislocation and heterodeformation induced (HDI) can be achieved in the structure by regulating the widths of zones with different grain sizes.