The effect of added oversized elements on the microstructure of binary alloy nanoparticles

Molecular dynamics simulations are used to investigate the microstructures of Cu-Ni nanoparticles with different concentrations of oversized atoms added to them. A many body second moment tight binding approximation potential is adopted to model the interatomic interactions. The Honeycutt-Anderson (HA) pair analysis technique is adopted to analyse in detail the transformation between local structures at different temperatures. From the simulation results, at temperatures higher than the melting point, the nanoparticles are in a liquid state and an icosahedral local structure is most frequently found inside the nanoparticles. At temperatures beneath the melting point, the fraction of FCC local structure increases with decreasing concentrations of the larger size atoms, whereas a larger fraction of amorphous structure still remains in the solid state for higher concentrations of oversized atoms. This is because the effects of distortion and misfit are more significant for a nanoparticle having a higher concentration of oversized atoms.