Divergent Trends in Surface Atomic Segregation During Rapid Heating of Fe-Ni-Cr-Co-Cu High-Entropy Alloy Nanoparticles: A Molecular Dynamics Study

Abstract As a crucial component in additive manufacturing, understanding the melting process of high-entropy alloy nanoparticles (HEAs-NPs) is indispensable for achieving high-precision and high-performance additive manufacturing components. In this study, molecular dynamics simulations were employed to investigate the different trends in surface atomic preferences during the heating and rapid melting processes of Fe-Ni-Cr-Co-Cu HEAs-NPs under various sizes and melting rates. The results indicate that the surface structure of the NPs remains stable before reaching the melting point; once the melting point is attained, the surface melts rapidly first, followed by the overall melting of the NP. During the heating process, Cu and Cr exhibit surface segregation phenomena before melting, and this trend remains stable, unaffected by NP size and heating rate. After reaching the melting point, Cu segregation at the surface intensifies, while Cr no longer segregates to the surface, and the trend of Fe segregation at the surface decreases as the heating rate increases. Furthermore, we conducted an in-depth analysis of the causes of these different trends in surface atomic preferences during the heating and melting process from the perspectives of average atomic potential energy. Our research reveals the melting characteristics and surface atomic preference trends of Fe-Ni-Cr-Co-Cu HEA-NPs, providing valuable insights for the use of HEA-NPs in additive manufacturing.