Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

Abstract

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 void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces 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 Influence of Pore Size on the Indentation Behavior of Metallic Nanoporous Materials: A Molecular Dynamics Study

“…A previous work by Yuan and Wu [ 20 ] studied the effects of the relative density and the pore diameter on the adiabatic uniaxial compression behavior and the related atomic-level deformation mechanisms in nanoporous copper using MD simulations. Herein, we demonstrate that the pore size itself plays a key role in the resulting mechanical behavior of metallic nanofoams during nanoindentation, and we introduce a formalism to take it into account in the analytical modeling of the mechanical properties of these materials.…”