In this study we have focused on biocompatibility and osteoinductive capacity analysis of self-manufactured single-phase (HAP) and two-phase (HAP and β-ТСР) bioactive ceramics with various chemical modifications (Fig. 1). We demonstrate a reduction in solubility for all analyzed composite after the treatment with H2O and H2O2, accompanied by an enhancement in adsorption activity. This modification also resulted in an increase in micro- and macroporosity, along with a rise in the open porosity. Adipose-derived mesenchymal stromal cells demonstrated excellent cell adhesion and survival when cultured with these ceramics. Calcium phosphate ceramics (H-500, HT-500, and HT-1 series) stimulated alkaline phosphatase expression, promoted calcium deposition, and enhanced osteopontin expression in ADSCs, independently inducing osteogenesis without additional osteogenic stimuli. These findings underscore the promising potential of HAP-based bioceramics for bone regeneration/reconstruction.

The introduction of high-entropy alloys, notable for their increased hardness and thermal stability, gave impetus to the study of their properties in coatings. High-entropy metal coatings are characterized by high hardness, ranging from 7 to 19 GPa. The general laws governing the influence of various parameters on the mechanical properties of high-entropy metal coatings were analyzed. Single-layer metal, nitride, oxide, and carbide coatings and multilayer nitride coatings from high-entropy alloys produced by different deposition techniques were examined. The phase composition, structure, hardness, elastic modulus, and friction coefficient of the coatings were determined. The mechanical properties of high-entropy coatings, along with those of cast alloys, depend on the lattice parameter. With increase in the lattice parameter in bcc metal coatings, the elastic modulus and hardness decrease. The increased hardness of vacuum high-entropy coatings contributes to decrease in their friction coefficient compared to the cast state. The influence of pressure in the sputtering chamber and the voltage applied to the substrate on properties of the nitride coatings was established. The capabilities of producing thick (up to 80 μm) coatings combining metal and nitride interlayers from high-entropy alloys and determining their properties were shown. For the high-entropy carbide in the TiZrNbVTaHf system, the influence of the lattice parameter on hardness was revealed. The lowest friction coefficient (0.05) was observed in high-entropy oxide coatings. The high-entropy coatings showed high hardness. A hardness level of 19 GPa was reached for a metal coating based on the TiZrNbTaHfCr alloy, 63 GPa for a nitride coating based on the TiZrNbVHf alloy, and 48 GPa for a carbide coating based on the TiZrNbVHfTa alloy. The analysis showed that nitride coatings were the hardest, while the lowest friction coefficient was possessed by oxide coatings.

The influence of electron concentration, mixing enthalpy, and dimensional mismatch on the lattice parameter, elastic modulus, and normalized hardness of fcc high-entropy alloys (HEA) is studied. The lattice parameter, which determines the elastic modulus of HEA, is influenced by both the electron concentration and the mixing enthalpy. A rectilinear dependence of the normalized hardness of these alloys on the dimensional discrepancy is established. Formulas for calculating the hardness and the elastic modulus for hard-soluble HEA with fcc lattice are proposed.

The composition and microstructure of the targets used in the magnetron sputtering (MP) method may change during its operation, especially if the target is a multicomponent alloy. Therefore, the information on the composition and microstructure of the sputtered region of the target, namely, the groove, which forms on the target over time, makes it possible to predict changes in the properties of the film. The targets for our experiments were fabricated from CoCrCuFeNi, CoCrCuFeMnNi and AlCoCrCuFeNiV high-entropy alloys (HEAs). Scanning electron microscopy (SEM) and chemical microanalysis were utilized to study the structure and composition of the grooves on the targets at the beginning and at the end of the targets service life. The results of the investigations allowed to derive the following conclusions: (1) signs of melting found on the surface of the grooves indicate to high temperatures arising on the targets during their sputtering; (2) a new type of preferential sputtering effect has been established, the main condition of which is the presence in the target composition of inclusions of a component whose sputtering coefficient is noticeably higher than that of the others; (3) the formation of a specific microrelief on the target surface is a consequence of the combined action of two factors: high temperature and sputtering.

The phase composition, type II microstresses, and coherent scattering domains (CSDs) of multicomponent (medium- and high-entropy) bcc solid solutions with an average electron concentration, Csd, ranging from 4.6 to 5.47 e/a were studied. The effect of these characteristics on the hardness and Young’s modulus was analyzed. The alloys were melted in a MIFI-9 vacuum arc furnace using components with a purity of at least 99.5 wt.%; the ingots were remelted six times. The hardness and Young’s modulus of the alloys were determined from nanoindentation curves plotted with a Micron Gamma unit under a load from 0.98 to 2.94 N using a Berkovich diamond pyramid under automated loading and unloading. A relatively small change in the quantitative chemical composition of the samples led to a noticeable change in the lattice parameter, type II microstresses, CSDs, microhardness, and Young’s modulus. The greatest possible type II microstresses and minimum CSD sizes were observed for the alloys characterized by high average mismatch between the atomic sizes of their constituent elements. Increase in the electron concentration in the alloys led to higher hardness and Young’s modulus and lower lattice parameter. Increase in the type II microstresses was also accompanied by higher hardness and Young’s modulus. The microhardness H of alloys significantly exceeded that calculated with the mixture rule, Hmix, and was determined by solid-solution hardening (∆H = H – Hmix ranging between 2.9 and 6.4 GPa). Type II microstresses precisely calculated from the X-ray line width can be used for measuring the distortion of the solidsolution lattice and assessing solid-solution hardening. The relationship between the magnitude of solid-solution hardening, Young’s modulus, and lattice microdistortions (type II microstresses) was proposed.

We determined the effect of temperature on the hardness of thick (up to 100 µm) multilayer metal–metal nitride coatings. The nature of the change in hardness from temperature is individual for each of the tested multilayer coatings. The hardness of composite multilayer coatings largely depends on the ratio of components in the coating. For a multilayer metal–metal nitride composite coating based on molybdenum, the most refractory metal, with a component ratio of ~60 : 40, the hardness reaches 22 GPa at room temperature and a load of 1 kg, and at 900°C, it reaches 5.0 GPa.

The mechanical properties of a high-entropy CrMnFeCoNi2Cu alloy with an FCC lattice have been studied in a broad temperature range (4.2–350 K). The microhardness and Young’s modulus were measured at 300 K for two structural states. The temperature dependences of the yield strength, deforming stress, and strain rate sensitivity have been obtained. It was found that a high-strength state is realized in the alloy while maintaining high plasticity, over the entire temperature range. Empirical estimates of microscopic plasticity parameters and internal and effective stresses have been obtained using the thermally activated deformation model.

Coatings that consisted of the high-entropy AlTiCrVNbMo alloy were obtained by ion sputtering in plasma of compressed vacuum-arc discharge. The hardness of this metal coating is at the level of 18 GPa due to the presence of nanostructures along with cluster structures. Coatings made of this alloy in a nitrogen atmosphere are solid solutions based on an FCC lattice; the hardness of these coatings is in the range of 28–44 GPa and the combined elastic modulus is in the range of 255–340 GPa for coatings obtained in different technological modes. The hardness values of the oxide coatings are in the range of 33–35 GPa and the values of the combined elastic modulus are in the range of 280–290 GPa. The friction coefficient of this alloy depends on alloy hardness and ranges from 0.24 to 0.061.

The microstructure, phase composition, and mechanical properties of Ti–Cr–Al–Si–O alloys in ascast state and after annealing at 800°C have been studied. The as-cast alloys with 50 and 60 at.% Ti have two phases: a 1/1 α(TiCrSi) cubic approximant of the quasicrystalline phase and an intermetallic Cr2Ti(C14) Laves phase in different ratios. The as-cast alloy with a high titanium amount (72 at.%) contains three phases: a 1/1α(TiCrSi) approximant and two α-Ti and β-Ti solid solutions. The effect of annealing on the phase composition of the alloys has been studied. After annealing, the alloys with the lowest (50 at.%) and highest (72 at.%) Ti contents change their phase composition with the formation of Ti5Si3 silicide, while the alloy with 60 at.% Ti exhibits high thermal stability—its phase composition remains unchanged. The changes in hardness of the starting and annealed alloys have been examined by automatic indentation. The highest hardness, 11.7 GPa, is shown by the as-cast Ti 72 Cr 20 Al 2 Si 2 (SiO 2 ) 4 alloy. The hardness of the annealed Ti 50 Cr 30 Al 13 Si 2 (SiO 2 ) 5 alloy increases to 14.8 GPa.

An analytical formula is obtained from first principles describing the temperature dependence of the elastic modulus of borides, carbides, oxides, nitrides, composites, metals (both simple and transitional), as well as high-entropy alloys (HEAs).

The structural and chemical microinhomogeneity of the high-entropy TiVZrNbHfTa coating is studied. Electron microprobe analysis shows that the content of elements varies within 10 at.% at a distance of several nanometers. The density of (s + d) electrons remains constant. High-resolution electron microscopy used to examine the fine structure found clusters with the size close to the ‘periodicity’ of the chemical inhomogeneity.

Проведены комплексные исследовательские работы по получению способом электронно-лучевой плавки слитков жаропрочного сплава титана системы Ti-Si-Al-Zr-Sn, подвергнутых горячей пластической деформации для получения прутков-полуфабрикатов.Усовершенствована схема шихтовки и определены технологические параметры электронно-лучевой плавки слитков в модернизированной электронно-лучевой установке УЭ-208М

Проведені дослідження, метою яких є отримання технології збільшення експлуатаційного ресурсу гарматних стволів, використовуючи метод магнетронного розпилення, як метод, що дозволяє отримувати високоякісні покриття з точки зору фізико-технічних характеристик.

A rise in the condensation surface temperature during film growth is a result of energy dissipation on the condensation surface. An example of energy dissipation is the dissipation of chemical reaction heat, which releases during film deposition by reactive magnetron sputtering. The monitoring of the surface temperature during TiN film deposition by reactive (Ti–in–N2) and nonreactive (TiN–in–Ar or TiN–in–N2) sputtering methods has shown that this temperature is higher in the reactive case and decreases in the (TiN–in–Ar)–(TiN–in–N2) sequence of nonreactive sputtering modifications. It has been found that the composition and crystal structure of TiN films do not depend on the growth method and are identical to those of bulk titanium nitride. Based on these results, a formation mechanism of films obtained by the above methods has been suggested. In the case of reactive sputtering, the film was supposed to grow on the condensation surface through a reaction between titanium and nitrogen atoms. In the cases of nonreactive sputtering, the film forms from TiN molecules.

На прикладі керамічних електролітів на основі двоокису цирконію, кубічна будова яких стабілізована скандієм та церієм і які є сприйнятним модельним аналогом для дослідження впливу структури на руйнування крихких металевих матеріалів, вивчено вплив стану меж зерен на властивості полікристалів. Скануюча електронна фрактографія і імпедансна спектроскопія виявили два невідомі раніше типи структурних переходів в міжзеренних прошарках матеріалів при спіканні. Спостережувані переходи супроводжуються суттєвими змінами міцності та електричних властивостей.

Ìåòàëîçíàâñòâî òà îáðîáêà ìåòàë³â 1'2018 44 Структура і фізико-механічні властивості УДК 666.762.52 Межі поділу та їх вплив на властивості полікристалів.Частина 1 (огляд) О. Д. Васильєв, доктор фізико-математичних наук І. В. Бродніковська, кандидат технічних наук Є. М. Бродніковський, кандидат технічних наук С. О. Фірстов, доктор фізико-математичних наук, професор

Поступило в Редакцию 11 июля 2017 г

In spite of great efforts undertaken to produce and examine the properties of new high-entropy alloys (bulk or film alloys), the available information is still insufficient for creating scientific ideas that would connect the properties and process parameters of these alloys. We studied the dependence of the composition and structure of Co–Cr–Cu–Fe–Ni films deposited by magnetron sputtering on the physical parameter such as energy flux delivered to the growing film surface. This parameter is directly related to process parameters such as magnetron discharge current (Id) and substrate bias voltage (Ub). The films have a nanocrystalline microstructure and crystallize as a two-phase fcc and bcc solid solution with the following lattice parameters: a = 0.363 nm for the fcc phase and a = 0.294 nm for the bcc phase. Ion bombardment of the growing film induced by bias voltage Ub varying from 0 to –300 V in the substrate influences the film structure and composition. Thus, the films deposited at ~300 eV are noticeably depleted of copper, while the composition of the films deposited without ion bombardment is the same as that of the target. Greater energy flux delivered to the growth surface (higher Id and/or Ub in the substrate) increases the growth surface temperature, leading to grain coarsening and film texturing. The bcc phase also substantially decreases in volume, vanishing in the films deposited at Ub = –300 V. The films formed by the bombardment of ions with ≈100 eV energy showed the maximum (~19 GPa) microhardness.

An analysis of simple structures of the solid-solution non-ordered high-entropy alloys (HEAs) with a bcc crystal lattice has allowed us to determine the effect of various parameters on their physicomechanical properties. It was found that, as the hardness increases, the size mismatch results in a decrease in the modulus of elasticity; however, the normalized hardness characteristic increases. It has been found that, when the enthalpy of mixing of the bcc high-entropy alloys shifts to negative values, its effect on the hardness and modulus of elasticity is nonmonotonic. A formula for calculating the modulus of elasticity of high-entropy alloys with a bcc structure has been suggested that is based on the alloy composition and role of the most refractory metallic component.