Mechanical properties of crystalline and amorphous nickel nanoparticles: molecular dynamics simulation

Using the molecular dynamics method, a study was conducted on the compression deformation of nickel nanoparticles with crystalline and amorphous structures. It was shown that with an increase in the deformation rate, the strength of the nanoparticles increases, while an increase in temperature leads to a decrease in strength. During the deformation of monocrystalline nanoparticles, anisotropy of mechanical properties was observed. In particular, the compressive strength along the [111] and [110] directions was approximately 30–40% higher than the strength along the [112] direction. The following stages of deformation of monocrystalline nanoparticles under compression were identified: formation of flat contact patches at the interfaces with the compressing surfaces, cooperative rotation of the entire particle structure, formation of dislocations near the contact patches and their propagation. As the size of the monocrystalline particle decreased, the proportion of the structural rotation stage increased. With decreasing size of nanoparticles, both monocrystalline and amorphous, their strength increased, as well as the strain at which the maximum stress was reached. When compressing amorphous nanoparticles, in most cases, a phenomenon of densification and partial crystallization of the structure near the load application sites was observed, which became particularly pronounced upon reaching strains typically exceeding 8–10%.