  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.
