ATOMISTIC SIMULATION OF THERMALLY INDUCED STRUCTURAL TRANSFORMATIONS IN QUATERNARY Cu–Au–Pt–Pd NANOALLOYS WITH DIFFERENT MORPHOLOGIES

The results of molecular dynamics simulation of thermally induced structural transformations in four-component Cu–Au–Pt–Pd nanoalloys using the tight-binding potential are presented. The following initial configurations were chosen: a core–shell system in which the core corresponds to a multicomponent alloy with a uniform distribution of components (Cu–Au–Pt)@Pd, an onion structure Cu@Au@Pt@Pd, an alloy with a uniform distribution of components Cu–Au–Pt–Pd, Janus structures with asymmetric Cu/Au/Pt/Pd and symmetric distributions of components (Cu/Au/Pt/Pd/Pt/Au/Cu and Pd/Pt/Au/Cu/Au/Pt/Pd). Based on the analysis of temperature dependences of the potential part of the internal energy, the temperatures corresponding to the onset of the melting-crystallization phase transition were found, and the value of temperature hysteresis was estimated. Regularities in the change of these quantities depending on the rate of thermal action were established. Regularities of structure formation were analyzed, the dominant role of the fcc local environment was established, cases of occurrence of other crystalline structures (hcp and bcc) were revealed. Regularities of chemical segregation are described, confirming the possibility of existence of various scenarios of segregation behavior of components. Based on the original technique, estimates of the specific surface energy for multicomponent metallic nanoparticles (final configurations after a cycle of thermal action, including the melting-crystallization phase transition) were carried out. The value of the specific surface energy correlates with the stability of the final configurations corresponding to different initial configurations.