Effects of specimen size and apllied strain rate on the plastic flow of FCC metals
FCC金属塑性屈服的尺度效应和应变率响应

The simple shear molecular dynamics (MD) simulations are performed on single-crystal copper blocks to analyze the size and strain rate effects on face-centered cubic (FCC) metals. It is found that the yield stress decreases with the specimen size and increases with the strain rate. Based on the theory of dislocation nucleation, a modified power law is established to predict the scaling behavior of FCC metals, and it agrees well with the numerical and experimental data ranging all spatial domain from nano-scale to macro-scale. In the atomistic simulation at different applied strain rates, a critical strain rate exists for the single-crystal copper. Below it the yield stress is nearly insensitive to the strain rate, while above it the yield stress increases rapidly with increasing strain rate. Based on the results of the MD simulation, a strain rate model is introduced for the plastic yield stress of FCC metals at nano-scale.