Nanocomposites and nanomaterials
Deposition and growth of the AlCoCuFeNi high entropy alloy thin film: molecular dynamics simulation 
Kushnerov O.I., Bashev V.F., Ryabtsev S.I.
Department of Experimental Physics, Oles Honchar Dnipro National University. Gagarin ave., 72, Dnipro, 49010, Ukraine. 
E-mail: kushnrv@gmail.com

High entropy alloys (HEAs) are relatively new class of metallic materials developed by Yeh et al. in 2004. Such alloys usually contain from 5 to 13 major elements in equiatomic or near equiatomic concentrations (5 to 35%). Due to the high mixing entropy, multicomponent high entropy alloys typically consist of simple solid solutions with a BCC or FCC lattices. The majority of HEAs were investigated in the as-quenched or homogenized state, whereas much less attention was paid to the study of thin films of high-entropy alloys. However, HEAs are sometimes difficult to synthesize as bulk materials because very fast cooling rates are required to avoid the formation of complex crystallized phases and to freeze low ordered structures. Understanding the growth mode of complex multielement HEA films is an important research topic. 
In this paper, the processes of deposition and growth of thin films of AlCoCuFeNi HEA on the surface of monocrystalline silicon substrate were investigated using the LAMMPS software package. The simulation was carried out using the embedded atom model (EAM), the interaction between the silicon atoms was described using the Stillinger-Weber potential, and the interaction between the atoms of Al, Co, Cu, Fe, Ni, and the substrate was modeled using the Lennard–Jones potential. In total 18825 atoms were deposited on the substrate, and the thickness of the formed film reached ~ 3 nm. According to the results of the simulation, it was found that in the initial stages of growth the film represents an islet-like structure. Later, the growth of the islands and the formation of continuous coating begins. Due to the limited number of impinging atoms, a fully continuous film is not reached. At the characteristic sizes of islands ~ 2 nm, the process of crystallization begins. In accordance with common neighbor analysis, after the  4,53 ns of modelling, the simulated film contains a face-centered cubic (FCC) phase (content 15,1%), a body-centered cubic (BCC) phase (content 21,2%), a hexagonal close-packed (HCP) phase (content 22,4%) and an indefinite phase (content 41,3%), which, according to the analysis of the radial distribution of atoms, has an amorphous structure. The determined parameters of the lattice: FCC a = 0,3634 nm, BCC a = 0,2909 nm. The features of the distribution of the HCP phase atoms allows us to conclude that this phase consists partly of stacking faults in the lattice of the FCC phase, and partly of twins.