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Abstract-The influence of high-fluence ion irradiation of nanostructured (Ti, Hf, Zr, V, Nb)N coatings is revealed for the first time. The energy of irradiating helium ions is equal to 500 keV, and their fluence falls into the interval 5 × 10 16 -3 × 10 17 ions/cm 2 . The performance of the coatings in a nuclear reactor is simulated by conducting post-irradiation thermal annealing at 773 K for 15 min. The elemental composition, structure, morphology, and strength properties of the (Ti, Hf, Zr, V, Nb)N coatings are studied before and after irradiation. No considerable structural and phase modifications in the coatings are found after irradiation, except for the fact that crystallites in the coatings drastically reduce in size to less than 10 nm. Nor does the atomic composition of the coatings change. It is shown that the microhardness of the coatings depends on the fluence of irradiating ions nonlinearly. It can be argued that the (Ti, Hf, Zr, V, Nb)N coatings are radiationresistant and hence promising for claddings of fuel elements in nuclear reactors. DOI: 10.1134/S1063784215100187INTRODUCTION High-entropy nitride alloys, such as (Ti, Hf, Zr, V, Nb)N compounds, are of great interest owing to their unique properties. It was shown [1][2][3][4][5][6][7] that when the entropy extremely rises, relaxation has no time to proceed and the system remains nonequilibrium. This improves the operating performance of coatings, specifically, their properties such as strength, wear resistance, corrosion resistance, heat resistance, and hightemperature stability [1][2][3][4][5]. High entropy is achieved in a multicomponent single-phase disordered solid solution prepared by vacuum deposition. In this method, a coating is deposited on a substrate at a low temperature as a result of which the coating nucleation and growth rates are high. This feature adds to the entropy of the forming system and favors the formation of an ultra-fine-grained structure of the nanocrystalline film.As is known [8], the state of the system is described in terms of the thermodynamic potential function(1) where G is the internal energy, p is the pressure, V is the volume, T is the temperature, and S is the entropy.The stability of a thermodynamic system is characterized by a minimum of the Helmholtz free energy,

A multilayered nanocomposite designed for biomedical applications based on (TiAlSiY)N/CrN coating implanted by heavy Au − ions is studied. Ion irradiation produced formation in the upper-surface of local amorphous clusters. The obtained composite system was characterized by SEM-EDS, RBS, SIMS, HRTEM, STEM, and nanoindentation mechanical tests, inspecting microstructure, phase state, elemental composition and surface defectiveness. The range of ion impact with correlation to TRIM simulations amounted to 23.5 nm with visible dislocations and interstitial loops indicating the nanopores' creation up/lengthways to the interface boundary. Mechanical parameters remain stable with a slight decrease (less than 2%) in hardness along with an increase in ductility. The antibacterial effect was evaluated in vitro by agar-diffusion and time-kill (72 h) assessments to define both cell-killing mechanisms: dry surface-contact and cytotoxic golden ionsrelease into moist environment. The identified antibacterial activity within implantation was 2−2.5 times higher due to inhibition zone diameter and antibacterial rate increase. The Au − implanted composite exhibits excellent defense against Gram-negative and Gram-positive bacteria without appreciable surface contamination. Possible biophysical and chemical mechanisms of microorganisms' disruption and annihilation were proposed and analyzed. The present study shows that produced composite has large potential for use in biomedical areas.