Atomistic simulation for the size effect on the mechanical properties of Ni/Ni_3Al nanowire

摘要

The size dependence of the mechanical properties of Ni/Ni_3Al nanowires (NWs) was investigated with molecular dynamics (MD) simulations. The results indicated that the surface energy σ increased, and bulk modulus B and B/G ratio decreased with increasing the inverse of the nanowire perimeter of the NWs. The extrapolated values of surface energy σ_0 were 2.100 J/m~2 and 1.956 J/m~2 for the samples with surface atoms of pure Ni atoms and mixture of Ni and Al atoms, respectively. The size dependence of the bulk modulus was in good agreement with the prediction of the Birch-Murnaghan equation and the surface shell softening the bulk modulus. Finally, the B/G ratio indicated that the ductility/brittleness behaviors of the NWs depended mainly on the energy distributions of the surface shell, and the mechanisms of the ductility/brittleness of the NWs were studied in detail.