Effect of lattice distortion and nanovoids on the shock compression behavior of (Co-Cr-Cu-Fe-Ni) high entropy alloy

In this article, non-equilibrium molecular dynamics-based simulations were performed to study the effect of shock compression on the deformation governing mechanism of high entropy alloys (HEA). Quinary configuration of the alloy containing (Co-Cr-Cu-Fe-Ni) as primary elements were considered, and interaction between them was simulated with the help of embedded atom method potential. Hugoniot curves between P-Up and Us-Up were captured for HEA that agrees qualitatively and quantitatively with results reported using higher fidelity simulations and experimental techniques. Single-crystal HEA was subjected to shock compression and ultra-short pulse at piston velocities above and below the Hugoniot elastic limit. To capture the dynamics of the shock wave propagation in single-crystal HEA, spectra-temporal distribution of pressure and velocities were captured as a function of time from the onset of the shock wave. It was predicted from atomistic simulations that the insertion of voids in the path of shock front helps in dispersing the energy, as well as reducing the speed of shock propagation. Voids significantly affect the shock deformation governing mechanism in the crystal of HEA, and onset plastic deformation, even at piston velocities below the Hugoniot elastic limit. To capture the effect of lattice distortion in HEA, average atom configuration was also developed. It was predicted from the simulations that the effect of lattice distortion helps in blunting the shock front and diluting its speed of propagation. The lattice distortion effect is more dominant at lower simulation temperatures and lower piston impact velocities.

Automated summary

This article investigates the effects of shock compression on the deformation mechanism of high entropy alloys (HEA) using non-equilibrium molecular dynamics simulations. The simulations confirm the qualitative and quantitative agreement between the Hugoniot curves obtained and results reported using higher fidelity simulations and experimental techniques. The study shows that inserting voids in the path of the shock wave helps disperse the energy and reduce the speed of shock propagation, while lattice distortion blunts the shock front and dilutes its speed of propagation.