Molecular dynamics simulation and characterization of the low-temperature subsurface deposition of FeCoNiCrMn high-entropy alloy thin films

The high-quality preparation of high-entropy alloy (HEA) films at low temperatures (<100 °C) is a significant challenge in the field of materials science. This study employs molecular dynamics simulations (LAMMPS) to systematically investigate the interaction between ultra-low-energy ion beams (100 eV) and equiatomic FeCoNiCrMn high-entropy alloys, proposing a “thermal spike-defect” mechanism. The findings reveal that at low temperatures (0 K), deposition on the surface layer forms an ordered film with numerous defects. At 350 K, atoms diffuse into the subsurface layer, forming stress gradients, which reduce structural ordering while enhancing diffusion and reducing defects, ultimately leading to the formation of a subsurface alloyed structure. Radial distribution function (RDF) analysis indicates that Ni and Co exhibit strong interaction forces with the Fe substrate. This study elucidates the temperature-dependent regulation of defect formation, atomic diffusion, and mechanical properties, thereby providing theoretical foundations for developing high-performance HEA films fabricated at low temperatures.