In this work, we aim at studying the strength of metallic specimens with dimensions at the sub-micrometer scale. In particular, single-crystals with a Face-Centered Cubic (FCC) lattice structure were deformed under compression in a Molecular Dynamics simulation. These nanoparticles were initially constructed in their minimum energy configuration, known as "Wullf Shape", and were compressed along their crystallographic direction. We conclude that the deformation is controlled by nucleating dislocations at the vertices, and there is a strong dependence of the yield strength on the nanoparticles size, i.e. there is an inverse relation between the strength and the characteristic microstructural length scale. This dependence can be described by a power law, from which it is suggested that the resolved shear stress needed to nucleate a dislocation at the nanoparticle upper or lower vertices obeys a power law, with an exponent that is ascribed to the stress gradient near the vertices along the slip plane. Due to this fact, the exponent did not depend on the material properties and it was found to be almost uniform for all FCC metals we checked. Its values vary in the range of 0.49-0.54 . However, the prefactor of the power law dependency was found to be material dependent and we propose here an extended model for a nucleation of a partial dislocation at a strong stress gradient to rationalize these results.
