Nanoalloys have received considerable attention during recent decades because of their diversities in geometries and performances that are not observed in monometallic clusters. Nanoclusters may consist of identical atoms or molecules, or two or more different species. For bimetallic clusters (AmBn), structures as well as degree of segregation significantly depend on their sizes and compositions.

In the present work, molecular dynamics simulations are performed to explore the structural and thermodynamic changes of nanoalloys with the addition or removal of one atom during cooling. The simulation results reveal that there are significant differences in the structural diagrams of the nanoalloys from potential energy, free energy, and entropy as well as visually atomic packing images and pair distribution functions. There are apparent effects of compositions and sizes on the structural transitions as well as the transition process. The results also show that during the cooling processes, there are multi-structural transition processes for the nanoalloys having different compositions, and most of the nanoalloys show a transition from a liquid state to a core−shell metastable packing structure and then to an Ih packing structure. The compositions and atom numbers as well as the shape also affect the thermodynamic quantities. The findings contribute to the understanding of fundamental issues involved in alloying between Cu and Ag metals and are important for the precise control of the preparation of Cu−Ag nanoalloys with specific structures and properties.