Atomistic deformation mechanisms in copper nanoparticles

The compression of the face-centered-cubic copper nanosphere is investigated by using molecular dynamics simulations. In the elastic regime, the response of nanosphere can be described by the classic Hertzian contact theory. The plastic deformation begins with the nucleation of partial dislocations from the contact edges. These partials dislocations glide and intersect to form pyramid sessile dislocation locks, which play the key role in the hardening of incipient plasticity. As the compression increases, partial dislocations nucleate from the free surface and their expansion leads to deformation twinning, which not only enhances the strength but also ductility.