Tuning dynamic mechanical properties of Cu50Zr50 nanoglasses/ nanopolycrystalline Cu composites investigated by molecular dynamics simulation

Abstract

Nanoglasses/nanopolycrystalline (NGNP) composites have emerged as a promising approach to balance the strength and plasticity of metallic glasses. Herein, the shock responses of five Cu50Zr50 NGNP composites are investigated via molecular dynamics simulations under a shock velocity of 0.5 to 2.0 km/s. The simulation results reveal that with an increasing fraction of nanocrystalline grains, the Hugoniot pressure, shear stress, and spall strength of the composites are enhanced, while their atomic strain decreases under shock loading. Additionally, due to the dominant structure type changes from an amorphous structure to a crystal structure, the deformation mechanism transforms from the growth of shear transformation zones to dislocation slip, phase transition, and amorphization as the impact velocity increases. In terms of the spallation, the spall strength of the composites rises initially and then declines due to the competing mechanisms of strain rate hardening and shock-induced softening.