Molecular Dynamics Modeling of Contact Melting in Bimetallic Nanosystems

Isothermal molecular dynamics and embedded atom method are used to study patterns and mechanisms of contact melting (CM) in eutectic bimetallic Ag–Cu systems with different geometries: a plane-parallel Cu₅₉₅₆–Ag₄₃₃₅ bilayer consisting of layers of Cu₅₉₅₆ and Ag₄₃₃₅ of the same thickness, and a system of two Ag₁₀₁₂ and Cu₁₄₄₅ nanoparticles in the form of rectangular parallelepipeds. In the latter, CM is complicated by a number of other processes, including the daughter nanoparticle acquiring a spherical shape, surface diffusion, and the surface segregation of Ag. The CM kinetics of the bilayer is studied, including the kinetic dependence of the potential part of the specific internal energy. This dependence is used to identify and analyze stages of CM. The temperature dependence of the rate of CM is analyzed, and the coefficient of mutual diffusion is estimated. Similar molecular dynamics experiments are performed using Ni–Cu nanosystems. As expected, CM is not observed in these systems because the Ni–Cu alloy is not eutectic.