Molecular Dynamics Simulation of the Interaction between Cracks in Single-Crystal Aluminum

TL;DR

This study uses molecular dynamics simulations to explore how cracks interact and propagate in single-crystal aluminum, revealing complex mechanisms like micro-crack growth, dislocation activity, and the influence of crack interactions on material strength.

Contribution

It provides detailed atomic-scale insights into crack interactions and propagation mechanisms in single-crystal aluminum, highlighting effects on strength and phase transformation.

Findings

Crack interactions inhibit phase transition at crack tips.

Interaction strength depends on crack distance and size.

Crack interactions influence material strength but not elastic modulus.

Abstract

The interaction between cracks, as well as their propagation, in single-crystal aluminum is investigated at the atomic scale using the molecular dynamics method and the modified embedded atom method. The results demonstrated that the crack propagation in aluminum is a quite complex process, which is accompanied by micro-crack growth, merging, stress shielding, dislocation emission, and phase transformation of the crystal structure. The main deformation mechanisms at the front of the fatigue crack are holes, slip bands, and cross-slip bands. During crack propagation, there are interactions between cracks. Such interactions inhibit the phase transition at the crack tip, and also affect the direction and speed of crack propagation. The intensity of the interaction between two cracks decreases with the increase of the distance between them and increases with increasing crack size. Moreover, while this interaction has no effect on the elastic modulus of the material, it affects its strength limit.