Atomistic Simulation of Shear Mode Deformation of Nanocrystalline Copper with Different Grain Sizes

摘要

Mechanical deformation of nanocrystalline copper has been simulated by means of molecular dynamics. The embedded atom method (EAM) potential was adopted for calculating the interatomic interaction. Samples with different grain sizes, 2.7 and 4.2 nm, were prepared by sintering spherical nanocrystals of different sizes. About 38000 atoms were contained in the sample, and a heterogeneous structure composed of crystalline and amorphous regions was realized. A shear mode strain was applied to the sample by sliding its upper and lower parts. The simulation was performed under free boundary condition for the surfaces perpendicular to the shear plane, and the stress-strain relation was obtained. The determined flow stress was lager for larger grain sample, namely, the inverse Hall-Petch effect was observed. Simulations for temperature and strain-rate dependences of the flow stress were also performed.