Dislocation nucleation in shocked fcc solids: effects of temperature and preexisting voids

TL;DR

This study uses molecular dynamics simulations to analyze how temperature and preexisting voids influence shock-induced dislocation nucleation in fcc Lennard-Jones solids, revealing key effects on the Hugoniot elastic limit.

Contribution

It provides a quantitative analysis of dislocation nucleation behaviors considering temperature and voids, highlighting the impact of void size on the Hugoniot elastic limit.

Findings

HEL decreases linearly with temperature in perfect crystals.

Voids significantly lower the HEL, especially with larger radii.

HEL becomes insensitive to temperature in the presence of large voids.

Abstract

Quantitative behaviors of shock-induced dislocation nucleation are investigated by means of molecular dynamics simulations on fcc Lennard-Jones solids: a model Argon. In perfect crystals, it is found that Hugoniot elastic limit (HEL) is a linearly decreasing function of temperature: from near-zero to melting temperatures. In a defective crystal with a void, dislocations are found to nucleate on the void surface. Also HEL drastically decreases to 15 percent of the perfect crystal when a void radius is 3.4 nanometer. The decrease of HEL becomes larger as the void radius increases, but HEL becomes insensitive to temperature.