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Refractory high entropy TiTaZrHfW-N/Si 3 -N 4 nano-layered alloy thin films are investigated to study the effect of nano-layered architecture and silicon (Si) mean content on their structural, mechanical, thermal properties and oxidation behavior. The films are deposited using direct current (DC) magnetron sputtering of separate Si and TiTaZrHfW targets. The Si mean content is controlled by tailoring the power discharge applied to the Si target. The deposition process led to a nano-layered architecture where Si 3 N 4 (amorphous) and TiTaZrHfW-N (nano-crystalized NaCl FCC type structure) are alternated. By increasing the thickness of Si 3 N 4 nano-layers, the Si mean content increases. All coatings are found to have good thermal stability after annealing under vacuum at 900 °C. Increasing Si mean content reduces the film's hardness; however, the annealing treatment at 900 °C improves it. A super-hardness of 41 GPa is found for the post-annealed Si-free film. Si 3 N 4 nano-layers enhance the oxidation resistance at elevated temperatures of 600, 700, and 800 °C. This oxidation resistance is further enhanced by increasing the nano-layer's period and also by increasing the density of the films. [Display omitted] • Refractory high entropy TiTaZrHfW-N/Si 3 -N 4 nanolayered thin films deposited by reactive magnetron sputtering. • Effect of Si alloying on TiTaZrHfW(-N) properties. • Nanolayered architecture structure alternating Si 3 N 4 (amorphous) and TiTaZrHfW-N (nano-crystalized NaCl FCC). • Si 3 N 4 nano-layers enhance oxidation resistance at elevated temperatures (600, 700, and 800 °C). • Oxidation resistance further improves with increased nano-layers period and film density. [ABSTRACT FROM AUTHOR]

(AlTiZrHfTa) 1−x N x refractory high entropy films (RHEFs) were deposited by direct current magnetron sputtering in various nitrogen ratios (R N2 = N 2 /(Ar+N 2)) on flat glass, silicon and sapphire substrates. The nitrogen-free film is amorphous while the nitrides are single-phased solid solutions with Face-Centered Cubic (FCC) structures. The hardness increases from 6.4 GPa for the nitrogen-free film to 25.3 GPa for the film obtained at R N2 = 20%. A preferred orientation from (111) to (200) occurs when R N2 increases from 5% to 50%. H/E and H3/H2 reports show high values for the film deposited at R N2 = 20% compared to that at 10%. However, this latter has the best compromise in terms of mechanical properties related to a lower residual stress value. The nitrides films obtained with R N2 ≥ 5%, are thermally stable at 800 °C for 3 h under vacuum. Compared to the metallic film they show an improved oxidation resistance. In fact, the K p constant of the nitride (R N2 =20%) is lower (1.22 10−7 g2 cm−4 h−1) than that of the nitrogen-free film (1.77 10−6 g2 cm−4 h−1). The corresponding activation energies (E a) are respectively calculated at 94.8 KJ. mol−1 and 45.5 KJ.mol−1. After oxidation process, TEM analysis reveal the formation of homogeneous mixed oxide. • AlTiZrHfTa(-N) films were deposited by reactive DC magnetron sputtering. • The metallic film is amorphous, while the nitrides exhibit FCC phase structure. • The film deposited at R N2 = 10% had the best compromise of mechanical properties. • The nitrides exhibit a better oxidation resistance compared to the metallic film. [ABSTRACT FROM AUTHOR]

This article presents the evidence for the significant effect of copper accelerating the bacterial inactivation on Ti-Nb-Ta-Zr (TNTZ) sputtered films on glass up to a Cu content of 8.3 at.%. These films were deposited by dc magnetron co-sputtering of an alloy target Ti-23Nb-0.7Ta-2Zr (at.%) and a Cu target. The fastest bacterial inactivation of E. coli on this later TNTZ-Cu surface proceeded within ∼75 min. The films deposited by magnetron sputtering are chemically homogenous. The film roughness evaluated by atomic force spectroscopy (AFM) on the TNTZ-Cu 8.3 at.% Cu sample presented an RMS-value of 20.1 nm being the highest RMS of any Cu-sputtered TNTZ sample. The implication of the RMS value found for this sample leading to the fastest interfacial bacterial inactivation kinetics is also discussed. Values for the Young’s modulus and hardness are reported for the TNTZ films in the presence of various Cu-contents. Evaluation of the bacterial inactivation kinetics of E. coli under low intensity actinic hospital light and in the dark was carried out. The stable repetitive bacterial inactivation was consistent with the extremely low Cu-ion release from the samples of 0.4 ppb. Evidence is presented by the bacterial inactivation dependence on the applied light intensity for the intervention of Cu as semiconductor CuO during the bacterial inactivation at the TNTZ-Cu interface. The mechanism of CuO-intervention under light is suggested based on the pH/and potential changes registered during bacterial disinfection. [ABSTRACT FROM AUTHOR]

In the last decades, refractory high entropy thin films have attracted more attention due to their superior properties at high temperatures. Besides the thermal stability, these new materials present good mechanical properties at high temperatures, which is interesting compared to conventional alloys. TiTaZrHfW(N) films are deposited by reactive magnetron sputtering in various argon/nitrogen atmospheres. Optical emission spectroscopy is performed to analyze the target poisoning conditions and optimize the deposition parameters. The nitrogen flow rate ratio R N = Φ N2 /(Φ N2 + Φ Ar) is varied from 0 to 29 %. XRD analyses show a phase transition from amorphous to B1(NaCl) single phased films once the nitrogen is added. For all nitrides, an out-of-plane {111} preferential orientation is observed, except for R N = 9 %, for which it changes to {200}. The morphology of the films changes from compact to columnar when the nitrogen ratio exceeds 5 %. The hardness and Young's modulus are also studied and present evolution with maximum values, 29 GPa and 257 GPa for R N = 9 % respectively. All nitrides show good thermal stability under vacuum at 800 °C for 3 h, compared to nitrogen-free metallic film, for which phase transition occurs. Nitrides show improved oxidation resistance compared to that of metallic film. • New refractory high entropy TiTaZrHfW(N) thin films nitrides deposited by magnetron sputtering. • Target poisoning in reactive mode was analyzed using Optical Emission Spectroscopy. • Effect of nitrogen content on microstructure, mechanical properties and oxidation has been studied. • Good thermal stability at high temperature was obtained. [ABSTRACT FROM AUTHOR]

There is a growing interest in the design of high entropy alloys due to their remarkable properties and applications in various fields such as aerospace, medical and automotive. AlTiTaZrHf(-N) high entropy metal-sublattice nitrides were deposited in various argon‑nitrogen gas mixtures on glass and silicon substrates. X-ray diffraction analyses reveal a transition from amorphous to an FCC single phase by increasing the nitrogen content. The films have compact or columnar morphology depending on the nitrogen flow rate. Energy dispersive spectroscopy analysis shows a decreasing of the matals content as the nitrogen flow rates ratio R N2 = N 2 /Ar + N 2 increases. XPS surface analysis reveal the formation of nitrides when the nitrogen is introduced. Evolution of hardness and Young's modulus are discussed and the maximum values are obtained for a flow rates ratio R N2 of 10% at 27.67 GPa and 205.56 GPa respectively. The same film reveals good tribological properties compared to other films. This work conclusively demonstrates that high entropy metal-sublattice nitrides can be generated in an efficient way with tunable properties. • Multicomponent AlTiTaZrHf(-N) deposited by reactive magnetron sputtering • Effect of nitrogen content on microstructure, mechanical properties and tribological performance studied • H and E are monitored by controlling the stoichiometric of N/Me. [ABSTRACT FROM AUTHOR]