A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from voidsurfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from voidsurfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.
The authors would like to acknowledge the financial support of the National Key Basic Research Program of China (Grants No. 2012CB932203 and No. 2012CB937500) and NSFC (Grants No. 11222224, No. 11472286 and No. 11021262). The simulations reported were performed at Supercomputing Center of Chinese Academy of Sciences.