Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu-Ag and Cu-Ni

We used molecular dynamics (MD) to obtain an atomistic description of the melting, glass formation, and crystallization processes in metal alloys. These studies use the quantum Sutton-Chen many-body potentials for Cu, Ni, and Ag to examine the ${\mathrm{Cu}}_4{\mathrm{Ag}}_6$ and CuNi alloys. Using cooling rates in the range of $2\times {10}^{12}$ to $4\times {10}^{14}\mathrm{K}/\mathrm{s},$ we find that CuNi and pure Cu always form a face-centered-cubic (fcc) crystal while ${\mathrm{Cu}}_4{\mathrm{Ag}}_6$ always forms a glass (with $T_g$ decreasing as the quench rate increases). The crystal formers have radius ratios of 1.025 (CuNi) and 1.00 (Cu) while the glass former (CuAg) has a ratio of 1.13, confirming the role of size mismatch in biasing toward glass formation.