Thermal stability of Al-Cu-Fe-Cr-Ni high entropy alloy bulk and nanoparticle structure: A molecular dynamics perspective

Understanding the thermal stability of high entropy alloy nanoparticle (HEA NP) is critical for developing high-temperature nanojoining technique. Molecular dynamics (MD) simulation is employed to investigate the thermal stability of Al, Cu, Fe, Cr and Ni HEA NP, and is compared with that of bulk HEA. Potential energy is calculated for determining the melting temperature, while structure evolution with temperature is characterized with adaptive common neighbor analysis and radial distribution function, for harvesting melting mechanisms. It is found that the HEA NP has comparable thermal stability of HEA bulk alloy structure; and a two-stage melting of HEA NP is found. The self-diffusivity of each element is calculated from the mean square displacement, and Cr atoms have the highest self-diffusivity, leading to the migration of Cr atoms to the surface. This research initiates the MD simulation on HEA NP, and shed light on the advance of the nanojoining technique.