In this paper, we analyze effects of hot rolling on the shape, structure, texture, and properties of a Ti–4.5Al–3Mo–V alloy (VT14) titanium alloy. The phase composition, texture, and morphology of the formed phases in the initial state and after rolling are determined. The effect of the deformation degree between the passes on the formation of various components of the deformation texture and recrystallization is shown. The dependence of VT14 alloy widening during flattening under the action of hot deformation in one pass are analyzed. A decrease in the widening coefficient at a similar degree of deformation is noted. Relationships between the studied hot deformation routes, the α/β-phase ratio, the morphology of the secondary α phase, the development of recrystallization in the β phase, as well as the hardness and contact elasticity modulus of VT14 alloy were determined.

Grokhovskyite, CuCrS2, was observed in small sulfide inclusions (up to 50–80 µm) in Ni-rich iron (kamacite) of the Uakit iron meteorite (IIAB) in the Republic of Buryatia, Russia. The grain sizes of this mineral are usually less than 5 μm, and the biggest detected crystals are 10 × 5 μm in size. It is commonly associated with daubréelite, troilite, schreibersite, and, sometimes, with carlsbergite and uakitite. Within inclusions, the mineral forms elongated splintered crystals, or, rarely, needle-shaped grains in daubréelite. The grokhovskyite-containing associations in the Uakit meteorite seem to form due to high-temperature (>1000 °C) separation of Fe-Cr sulfide liquid, which is locally enriched in Cu, from Fe-Ni metal melt. Physical and optical properties of grokhovskyite are quite similar to those of synthetic CuCrS2: yellow–brown and non-transparent phase with metallic luster; Mohs hardness ≈ 4; gray to light gray color with yellow tint in reflected light; weak to medium bireflectance, anisotropy, and pleochroism; density (calc.) = 4.559 g/cm3. Grokhovskyite is structurally related to the Cr-containing disulfide minerals with general formula Me+CrS2 (where Me+ = Na, Cu, Ag), including caswellsilverite, NaCrS2; schöllhornite, Na0.3CrS2·H2O; and cronusite, Ca0.2CrS2·2H2O. Structural data were obtained for one grokhovskyite crystal using the EBSD technique. Fitting of the EBSD patterns for a synthetic α-CuCrS2 model (trigonal R3m; a = 3.4794(8) Å; c = 18.702(4) Å; V = 196.08(10) Å3; Z = 3) resulted in the parameter MAD = 0.57–1.16° (good fit). Analytical data for grokhovskyite (n = 36, in wt.%) are as follows: Cu—32.97; Cr—27.65; Fe—3.69; Ni—0.16; S—35.71; Na, Zn, V, Mn, and Co—below detection limit (<0.005 wt.%). The empirical formula is (Cu0.930Cr0.952Fe0.118Ni0.005)2.005S1.995; however, different concentrations of Fe are indicated in two individual grains of grokhovskyite (0.09–0.17 apfu). Such variations may be explained by Fe incorporation in the grokhovskyite structure according to the scheme IVCu+ + VICr3+ → IVFe2+ + VIFe2+. The three main bands (near 110, 250, and 310 cm−1), which are common of synthetic CuCrS2, were observed in the Raman spectra of grokhovskyite.

Background: Glycerolates of biogenic elements are of interest because of their pharmacological activity. Some of them are used as active substances in agents for topical application and as biocompatible precursors in sol-gel synthesis of bioactive materials. Objective: In this work, morphostructural feature, ability to hydrolyze, and the pharmacological activity of previously synthesized iron(III) monoglycerate were studied. Methods: Analytical techniques, including SEM, TEM, XRD, TGA, IR spectroscopy, DLS and ELS, were used. Hemostatic activity was studied in vivo, and primary toxicological studies were carried out on experimental animals. Antimicrobial activity was studied using the agar diffusion method. Results: When dispersed in glycerol, solid crystalline iron(III) monoglycerolate transforms into an amorphous state, forming aggregates with an average particle size of 250 nm (according to DLS data). It slowly hydrolyzes in water at room temperature, while hydrolysis does not take place in an aqueous glycerol media. Iron(III) monoglycerolate is nontoxic and exhibits pronounced hemostatic activity and low antibacterial activity (relative to the strain S. аureus). Conclusion: Iron(III) monoglycerolate can be considered a potential hemostatic agent, showing promise for topical application in medical and veterinary practice, as well as a novel biocompatible precursor in the sol-gel synthesis of practically useful substances.

The short-term mechanical properties of commercial corrosion-resistant nickel alloys based on Ni-Cr (Hastelloy® G-35® or UNS N06035), Ni-Mo (Hastelloy® B-3® or UNS N10675), and Ni-Cr-Mo (VDM® Alloy C-4 or UNS N06455, VDM® Alloy 59 or UNS N06059, and KhN62M-VI) systems were analyzed in the as-received state and after long-term (up to 5000 h) aging at 500–700 °C. All alloys exhibited moderate strength and high ductility in the as-received state. Under the influence of high temperatures, these alloys showed a tendency toward the decomposition of Ni-based FCC solid solutions and a change in mechanical properties. It was shown that the difference in chromium and molybdenum content in Ni-Cr-Mo alloys leads to the formation of secondary phases of various composition and morphology, which had varied influence on the short-term mechanical properties of the materials. Grain boundary precipitates had a negligible effect on the strength properties of the investigated alloys, while intragranular precipitates embrittled nickel-based alloys, reducing their possible application at high temperatures.

Методами дифференциальной сканирующей калориметрии, растровой электронной микроскопии, микрорентгеноспектрального и рентгеноструктурного фазовых анализов, микроиндентирования изучено влияние термического воздействия на структурно-фазовое состояние и физико-механические свойства сплава на основе орторомбического алюминида титана (О-сплава), полученного селективным лазерным сплавлением. Изменение режима селективного лазерного сплавления, а именно повышение величины относительной плотности энергии при синтезе с 49 до 97 Дж/мм3 приводит к эволюции характера пористости образцов после селективного лазерного сплавления: от пористости, связанной с непроплавом частиц порошка, к газовой пористости, наследуемой от пор в порошке. Фиксируемый в О-сплаве при селективного лазерного сплавления метастабильный β-твердый раствор при нагреве со скоростью 50 К/мин до 900 °С претерпевает распад в двух диапазонах температур 300–600 и 650–800 °С. Повышение температуры термообработки с 750 до 900 °С синтезированного О-сплава способствует уменьшению объемной доли и укрупнению размеров О-пластин, выделяющихся при распаде β-твердого раствора, что приводит к уменьшению эффекта дисперсионного упрочнения (роста твердости) и прироста модуля упругости. Рассмотрено влияние величины относительной плотности энергии при селективном лазерном сплавлении на химический состав синтезируемого О-сплава, стабильность фиксируемого β-твердого раствора к процессам распада и формируемый комплекс физико-механических свойств при термообработке. Using the methods of differential scanning calorimetry, scanning electron microscopy, micro-X-ray spectral and X-ray structural phase analysis, microindentation, the influence of thermal effects on the structural-phase state and physical and mechanical properties of an alloy based on orthorhombic titanium aluminide (O-alloy), obtained by selective laser melting, was studied. A change in the selective laser melting regime, namely an increase in the relative energy density during synthesis from 49 to 97 J/mm3 leads to an evolution of the nature of the porosity of samples after selective laser melting from porosity associated with non-melting of powder particles to gas porosity inherited from pores in the powder. The metastable β-solid solution fixed in the O-alloy during selective laser melting, when heated at a rate of 50 K/min to 900 °C, undergoes decomposition in two temperature ranges 300–550 and 700–800 °C. Increasing the heat treatment temperature from 750 to 900 °C of the synthesized O-alloy promotes reduce the volume fraction and the enlargement of O-plates released during the decomposition of the β-solid solution, which leads to a decrease in the effect of dispersion strengthening (hardness growth) and an increase in the elastic modulus. The influence of the relative energy density value during selective laser melting on the chemical composition of the synthesized O-alloy, the stability of the fixed β-solid solution to decomposition processes, and the complex of physical and mechanical properties formed during heat treatment is considered.

Electrode induction gas atomization (EIGA) is a perspective, cost-effective method for producing spherical intermetallic titanium powders used in additive manufacturing. This study investigates the morphology, microstructure, nanoindentation properties, chemical and phase composition of commercial pre -alloyed EIGA powder of the Ti 2 AlNb-based alloy. The effect of particle size distribution on flowability is studied. Ti-23Al-25Nb powder is characterized by a typical dendritic single beta-phase microstructure with almost homogeneous distribution of alloying elements. The dendriti & scy; body is slightly enriched with Nb and the dendritic boundaries are enriched with Al. The temperature ranges of phase transformations are studied using differential scanning calorimetry at a rate of 50 degrees / min. Several phase transformations including beta -iota omega 0 ; beta -iota O; O -iota beta+alpha 2 ; alpha 2 -iota beta are revealed during heating. The activation of the powder oxidation process at temperatures above 700 degrees C is observed.

Abstract—The methods of scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study the effect of alloying with zirconium (within 3 to 6 at H^3/ . -0emE_r^2 (Н is the hardness and Er is the resolved modulus of elasticity) associated with the wear resistance as compared to those for the widely used medical Ti–6Al–4V alloy. The compositions of the alloys and conditions of their treatment are determined, which allow us to obtain the combination of the highest-level properties.

The impact of selective laser melting (SLM) process parameters on the porosity, microstructure, phase and chemical composition, texture, and physical-mechanical properties of orthorhombic titanium aluminide Ti2AlNb (O-alloy) powder was studied using a range of methods, including hydrostatic weighing, scanning and transmission electron microscopy, X‑ray diffraction analysis, energy-dispersive X‑ray spectroscopy, microindentation, and compression testing. It was demonstrated that an increase in the volumetric energy density within the range of 28 to 139 J/mm3 led to the following effects: 1) increase in the relative density of the obtained O‑alloy from 97 to 99.9

This article presents the results of the modeling of the behavior of the titanium alloy Ti-3Al‑2.5V at the initial stage of extrusion of a tube billet. The influence of the gaps between the surfaces of the tool and the billet on the nature of its shape change and the strain state is discussed. In particular, the most deformed tube parts of the maximum (by modulus) strain tensor values are identified. The dependence of the Ti-3Al‑2.5V alloy tube extrusion force on the stroke of the pressure pad is calculated. The results of the calculation of the maximum forces and the forces at the steady-state stage are in good agreement with the data obtained under an industrial experiment. Horizontal extrusion leads to an asymmetry in the location of the deformation fields relative to the extrusion axis. Accordingly, an asymmetric distribution of properties arises in the extruded tube, which is experimentally confirmed using hardness measurements. Correspondence is established between the simulation data on the heterogeneity of the strain distribution over the wall thickness of the hot-pressed tube made of titanium alloy Ti-3Al‑2.5V, considering the pressing-out, with the results of micro- and X‑ray structural studies of the tube semifinished product obtained.

The use of glycerolates of biogenic elements as biocompatible precursors in sol–gel synthesis is an innovative direction and opens up new scientific and practical prospects in chemistry and technology of producing practically important biomedical materials, including hemostatic, antimicrobial, and wound healing materials. Using biocompatible precursors, silicon, zinc, boron, and iron glycerolates, new bioactive nanocomposite hydrogels were obtained by the sol–gel method. The composition and structural features of the hydrogels were studied using a complex of modern analytical techniques, including TEM, XRD, AES, and ESI MS. Hemostatic activity of the hydrogels was studied in the in vivo experiments; using the example of silicon-iron-zinc-boron glycerolates hydrogel, primary toxicological studies were carried out. Antimicrobial properties of hydrogels were studied using the agar diffusion method. The structural features of hydrogels and their relationship to medical and biological properties were revealed. It was shown that glycerolates hydrogels are non-toxic, and exhibit pronounced hemostatic activity, generally comparable to the commercial hemostatic drug Capramine. Antimicrobial activity is more pronounced for silicon-iron-zinc-boron and silicon-iron-boron glycerolates gel. The results obtained indicate that these glycerolates hydrogels are potential hemostatic and antibiotic-independent antimicrobial agents for topical wound healing applications in medical and veterinary practice.

Abstract—Differential thermal analysis, scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study changes in the structure, phase composition, microhardness, and contact modulus of elasticity of a heat-resistant alloy based on the Ti2AlNb titanium intermetallic compound, depending on the rate of colling (10–80°/min) from heating temperatures of 950 and 970°С. Using the results obtained, thermokinetic diagrams of high-temperature decomposition of the β(B2) solid solution are constructed.

Electrode-induction gas atomization (EIGA) is a promising and cost-effective method for producing spherical intermetallic titanium powders used in additive manufacturing. The present study investigates the morphology, microstructure, chemical and phase compositions, nanoindentation properties of a commercial pre-alloyed TiAl-based EIGA alloy powder. The Ti – 48Al – 2Cr – 2Nb powder is characterized by a spherical shape and dendritic structure with the dendrites enriched with Nb and the interdendritic areas enriched with aluminum and chromium. The temperature ranges of the phase transformations in the powder with precipitation/dissolution of phases α2 , α, γ, B2, (TiNb)Cr2 are determined using thermal analysis during heating and cooling in an inert atmosphere of argon at a rate of 50 K/min. Development of an oxidation process at the temperatures above 500°C and significant increase in its rate at the temperatures above 900°C is detected.

В статье проведен анализ влияния режима горячей прокатки на формоизменение, структурно-текстурное состояние и свойства титанового сплава ВТ14. Определен фазовый состав, текстура и морфология образующихся фаз в исходном состоянии и после прокатки по различным маршрутам. Показано влияние степени деформации между проходами на формирование различных компонент текстуры деформации и рекристаллизации. Проанализированы зависимости уширения при плющении от относительного обжатия при горячей деформации сплава ВТ14 в проходе. Отмечено уменьшение коэффициента уширения при близкой степени деформации с увеличением номера прохода. Определена взаимосвязь между влиянием исследованных режимов горячей деформации на соотношение количества α/β-фаз, дисперсность вторичной α-фазы в структуре, развитие процессов рекристаллизации в β-фазе и фиксируемым в сплаве ВТ14 уровнем твердости и контактного модуля упругости. The article analyzed the influence of hot rolling on the shape change, structure and texture and properties of the titanium Ti–4,5Al–3Mo–V (VT-14) alloy. The phase composition, texture and morphology of the phases in the initial state and after rolling were determined. The influence of the degree of deformation between passes on the formation of various components of the deformation texture and recrystallization is shown. The dependences of spreading during flattening during hot deformation of the VT14 alloy in a pass are analyzed. A decrease in the spread ratio at a similar degree of deformation was noted. The relationships between the hot deformation routes, the α/β phase ratio, the morphology of the secondary α phase, the development of recrystallization in the β-phase, and the hardness and contact elasticity modulus of the VT14 alloy were determined.

In situ X-ray diffraction studies of a hardened Ti–26 at

Исследованы морфология, микроструктура, химический и фазовый составы, свойства после наноиндентирования порошка промышленного сплава Ti – 48Al – 2Cr – 2Nb на основе алюминида титана TiAl, полученного методом электродно-индукционного газового распыления (EIGA). Установлено, что порошок характеризуется сферической формой частиц и дендритной структурой, обогащенной ниобием, а междендритные участки обогощены алюминием и хромом. Методом термического анализа при нагреве в инертной атмосфере аргона со скоростью 50 °C/мин определены температурные интервалы реализации в порошке фазовых превращений с выделением/растворением фаз — α2, α, γ, B2, (TiNb)Cr2. Установлено развитие процесса окисления порошка при нагреве выше 500 °C и существенное повышение скорости окисления при температурах выше 900 °C.

Методами гидростатического взвешивания, растровой и просвечивающей электронной микроскопии, рентгеноструктурного и микрорентгеноспектрального анализов, микроиндентирования, испытания на сжатие изучено влияние режима селективного лазерного сплавления (СЛС) порошка сплава на основе орторомбического алюминида титана Ti2AlNb (О-сплава) на пористость, структурно-фазовое состояние, химический состав, текстуру и физико-механические свойства получаемых образцов. Показано, что увеличение используемой в работе при синтезе объемной плотности энергии в диапазоне от 28 до 139 Дж/мм3 способствует: 1) повышению относительной плотности получаемого О-сплава с 97 до 99,9%, 2) усилению аксиальной текстуры с выраженным направлением 001 в фиксируемом β/B2-твердом растворе, 3) снижению содержания алюминия, повышению содержания ниобия в сплаве и менее значительному его обогащению кислородом. Обнаружено, что отделение от платформы построения и разрезка О-сплава в продольном сечении приводит к нарушению баланса остаточных напряжений в образцах, синтезированных на нагретой до 200 °С подложки, с образованием в них трещин. Выявлены характерные дефекты структуры сплава (поры, непроплавы, химическая неоднородность) после сплавления порошка. Определен комплекс физико-механических свойств, синтезированных О-сплавов (твердость – 390–430 НV, контактный модуль упругости – 91–98 ГПа, предел текучести при сжатии – 1060–1080 МПа, относительное укорочение при сжатии не менее 30%. Рассмотрена связь получаемого уровня свойств в О-сплаве с формируемым при синтезе структурно-текстурным состоянием. The influence of the of selective laser melting (SLM) process parameters of the alloy based on orthorhombic titanium aluminide Ti2AlNb (O-alloy) on porosity, microstructure, phase and chemical compositions, texture, physical and mechanical properties using the methods of hydrostatic weighing, scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy, microindentation and compression testing were studied. It was demonstrated that the increase in the SLM in the range of volumetric energy density from 28 J/mm3 to 139 J/mm3 contributes to: 1) the increase in the relative density of the resulting O-alloy coupons from 97 to 99.9%, 2) the intensification of the solidification <001>-fiber texture of β/B2-solid solution, 3) decrease in Al, increase in Nb content and lesser enrichment with oxygen in the as-built coupons. The separation the O-alloy from the platform and along the building direction results in the imbalance of residual stresses accompanied by the crack formation in samples fused on a substrate preheated at 200°C. The typical defects (pores, lack of fusion, chemical inhomogeneity) after SLM are discussed. A combination of physical and mechanical properties of the synthesized O-alloys coupons was determined (Vickers microhardness - 390...430 HV, contact modulus of elasticity – 91–98 GPa, compressive yield strength 1060–1080 MPa, relative shortening in compression of at least 30%. The relationship between the resulting level of properties and a microstructure-texture in an O-alloy state formed of as-built SLM samples are considered.

Anodic zirconia nanotubes are a promising functional medium for the formation of non-volatile resistive memory cells. The current–voltage characteristics in the region of low conductance of the fabricated Zr/ZrO 2 /Au memristive structures were studied in this work. For the first time, an analysis was made of the reversible mechanisms of formation and destruction of single quantum conductors based on oxygen vacancies, which participate in processes of multiple resistive switching between low- and high-resistance states in the nanotubular dioxide layer. An equivalent electrical circuit of a parallel resistor connection was proposed and discussed to describe the observed memristive behavior of the studied layered structures.

BACKGROUND:Nanocomposite glycerohydrogels based on biocompatible elementcontaining glycerolates are of practicular interest for biomedical applications. OBJECTIVE:Using two biocompatible precursors, silicon and iron glycerolates, a new bioactive nanocomposite silicon‒iron glycerolates hydrogel was obtained by sol-gel method. METHODS:The composition and structural features of the hydrogel were studied using a complex of modern analytical techniques, including TEM, XRD, and AES. On the example of experimental animals hemostatic activity of the hydrogel was studied, as well as primary toxicological studies were carried out. RESULTS:The composition of dispersed phase and dispersion medium of silicon‒iron glycerolates hydrogel was determined. The structural features of hydrogel were revealed and its structure model was proposed. It was shown that silcon-iron glycerolates hydrogel is nontoxic, and exhibits pronounced hemostatic activity. CONCLUSION:Silicon-iron glycerolates hydrogel is a potential hemostatic agent for topical application in medical and veterinary practice.

The impact of heat treatment on the structural-phase characteristics, physical and mechanical properties of an alloy based on orthorhombic titanium aluminide (O-alloy) produced by selective laser melting was investigated using differential scanning calorimetry, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis, and microindentation. Modifying the selective laser melting process parameters, specifically increasing the relative energy density from 49 to 97 J/mm3, results in the evolution of the porosity character of the samples after selective laser fusion. This transition is observed from porosity associated with the lack-of-fusion to the gas porosity inherited from the pores in the powder and gas entrapment during melting. The metastable β‑solid solution that is fixed in the O‑alloy during selective laser melting undergoes decomposition in two temperature ranges, 300–600 °C and 650–800 °C, when heated at a rate of 50 °C per minute up to 900 °C. An increase in the heat treatment temperature from 750 to 900 °C of the as-built O‑alloy results in a reduction in the volume fraction and an expansion in the thickness of the O‑platelets precipitated during the decomposition of the β‑solid solution. This phenomenon leads to a decline in the impact of dispersion hardening (hardness growth) and enhancement in the elastic modulus. This study examines the impact of volumetric energy density during selective laser melting on the chemical composition of the O‑alloy, the stability of as-built alloy to decomposition of β‑solid solution and the formation of a combination of physical and mechanical properties during heat treatment.