Molecular dynamics studies of the effect of intermediate Fe layer thickness on the enhanced strength and ductility of Cu/Fe/Ni multilayer

Abstract The synergistic strength-ductility is very important for composite materials. In this work, we studied the effect of intermediate layer thickness on the mechanical properties of Cu/Fe/Ni multilayer by introducing harder intermediate layer and non-coherent interface using molecular dynamics simulation, and revealed the relationship between the deformation mechanism and the strength-ductility from atomic scale. The results show that the yield strength and flow stress increase with increasing Fe layer thickness, but the tensile strain is opposite. Plastic deformation of all models are triggered by slipping of misfit partial dislocation originating from the decomposition of perfect dislocation on semi-coherent interface. However, the addition of Fe layer and non-coherent interface increases the resistance of dislocation crossing interface, and changes the dominant deformation mechanism from Shockley partial dislocation slipping to deformation twinning migration, thus improving the strength and ductility of multilayer. In addition, the evolution laws of the dislocation length and interface morphology as well as the shear strain distribution are discussed.