Molecular dynamic modeling of contact melting in bimetallic nanosystems

Regularities and mechanisms of contact melting (CM) in eutectic bimetallic Ag-Cu systems with different geometries, viz. a plane-parallel Ag₄₃₃₅-Cu₅₉₅₆ bilayer consisting of Cu5956 and Ag4335 layers of equal thickness and a system of two nanoparticles Ag1012 and Cu1445 in the form of rectangular parallelepipeds, are studied using isothermal molecular dynamics and the embedded atom method. In the latter case, CM is complicated by a number of other processes, including the acquisition of a spherical shape by the daughter nanoparticle, surface diffusion, and surface segregation of Ag. For the bilayer, the kinetics of CM is studied, including the kinetic dependence of the potential part of the specific internal energy. Based on this dependence, the CM stages are identified and analyzed. Moreover, the temperature dependence of the CM rate is analyzed, and the mutual diffusion coefficient is estimated. Similar molecular dynamic experiments are performed on Ni-Cu nanosystems. As one would expect, no CM is observed in these systems since the Ni-Cu alloy is not eutectic.