Structural and thermodynamic characterization of CuZr metallic glass nanoparticles: Insights from atomistic simulations

Metallic crystalline nanoparticles (NPs) have been shown to display intriguing size-dependent properties. However, the properties of metallic glass (MG) NPs remain largely unexplored. Using molecular dynamics simulations, we produce Cu₆₄Zr₃₆ MG NPs ranging in size from 1 to 20 nm by cooling molten systems at a relatively slow rate of 10⁹ K/s. Results indicate that NPs are coated with a Cu-rich layer with a thickness that increases with NP size. We employ various simulated rates of heating, from 10¹¹ to 10¹³ K/s, to determine the melting points of these NPs. The results show a significant decrease in the solidus temperature for NPs smaller than 10 nm. Furthermore, as NP size decreases, the fraction of Cu full icosahedra within the NPs increases, suggesting that smaller NPs are stronger and harder. These findings provide insights for designing heterogeneous metallic nanoglass materials that leverage the size-dependent properties of MG NPs.