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Magnetic properties of powder (Pr,Dy)FeCoB ferrimagnetic alloys and effects of annealing, surface states were analyzed. X-ray photoelectron spectroscopy and Mössbauer spectra of powders indicate the effect of surface states on phase composition and magnetic properties of the studied powder, if particles average size is smaller than 10 μm. Effect of stoichiometry on magnetic anisotropy was found. Thermal stability of anisotropy field was proved by replacement of Fe atoms with Co atoms.

Low-cycle fatigue of monocrystalline heat-resistant nickel-based alloy with crystallographic orientation 〈001〉 in rigorous loading is studied, at operational temperatures. The field asymmetry is expressed as a function of the number of cycles to failure. The fatigue curve is compared with predictions based on the short-term strength. [ABSTRACT FROM AUTHOR]

The authors study compacted materials obtained using different periods of the mechanical activation of mixtures whose compositions correspond to alloys of grades VKNA-1V and VKNA-4U, with subsequent electric spark sintering. The maximum strengths of the compacted materials are reached after 3.5 min of mechanical activation: 1200 MPa for VKNA-1V and 1100 MPa for VKNA-4U. [ABSTRACT FROM AUTHOR]

The results of experimental studies are given for specific formation of the structure of 1565chM alloy in the zone of intersection of welds. The welds are made using friction stir welding (FSW). It is found that the area where two welds intersect features a decrease in the average grain size from 5.2 to 3.3 μm. The measurements made for the moving force of the tool show that, upon moving from the welding section of 1565 chM alloy to the section of intersection with a preliminarily made weld, this value decreases from 11.75 to 3.8 kN. The metal in the area of intersection of two FSW welds has better strength properties. At the same time, the relative elongation is slightly lower here compared to the metal in the single weld stir zone. The static tensile tests reveal the highest strength properties in samples having longitudinal weld orientation relative to the direction of applying the load. Samples with intersecting welds are about 10–15% less strong. [ABSTRACT FROM AUTHOR]

Interaction of Pr/Dy with oxygen in nickel melts at PAr = 0.1 MPa and constant temperature was studied using the EMF instantaneous fixing method using a Mo[Cr/Cr2O3//ZrO2(MgO)//O(Nil)]Mo cell and certified sensors. Dependences a[O] = f[Pr/Dy, %] expressed in the form of logarithmic equations made it possible to compare them with each other in the concentration range of 0.001–0.2 wt % of each deoxidizer and determine that the deoxidizing ability of Pr is 1.7 times higher compared to Dy. The activity of oxygen a[O] in Ni–O–Al–(Pr/Dy) melts was calculated in comparison with Al at a concentration of 0.05 wt % of elements and its sevenfold decrease was shown for the first deoxidizer and elevenfold for the second. The morphology of nonmetallic inclusions in metallographic sections of Ni–O–Pr/Dy alloys has been studied, indicating that the inclusions are located along grain boundaries and have different configurations and a complex heterophase composition. Analysis of nonmetallic inclusions with the maximum content of deoxidizing element proved the existence of Pr/Dy oxygen compounds, which confirmed the data of thermodynamic and mass spectrometric studies. The average content of Zr in nonmetallic inclusions during the deoxidation of Pr is two times higher than in experiments during the deoxidation of Dy, which indicates the interaction of Pr/Dy with the EMF ZrO2 sensor and the preferential interaction of Pr compared to Dy and correlates with the data on the determination of a[O]. [ABSTRACT FROM AUTHOR]

γ'Ni3Al-based casting alloys have a lower density, higher melting point and resistance to oxidation, and a higher ceiling of operating temperatures than modern heat-resistant nickel alloys. The article discusses the features of the electronic structure and crystallization of domestic (such as VKNA/VIN) and the most advanced foreign (γ' + γ) low-alloyed γ'Ni3Al-based alloys (IC type), and experimental data on the nature of the structures formed during directional crystallization of alloys with different types of alloying and on the nature of the distribution of components in the γ'Ni3Al and γNi phases and structural components in the cellular-dendritic structure of single crystals with 〈111〉 and 〈001〉 crystallographic orientation are presented. The influence of heat treatment on the microstructure, distribution of alloying elements, and mechanical properties of the VKNA type alloys is investigated in a wide range of temperature–time parameters. A comparative analysis of the effect of temperature and duration of heat treatment and cooling rate after heat treatment on the heat resistance of alloys showed that, unlike other Ni3Al-based alloys, for single crystals from the VKNA type economically alloyed alloys and parts made from them (uncooled working blades of aviation gas turbine engines, nozzle apparatuses, jet nozzle spacers, and other parts of the hot path of gas turbine engines), a short-term heat treatment (1150°C/1 h) is necessary and sufficient to relieve casting stresses. The alloys demonstrate high heat resistance at 1100–1200°C and the ability to withstand short-term casting temperatures up to 1250–1300°C. [ABSTRACT FROM AUTHOR]

We demonstrate that an increase in the area of fused sections relative to the total area of the construction platform deteriorates the quality of the recycled powder owing to accumulating oxidized emissions. The quality of synthesized material deteriorates both as a result of cross-contamination caused by oxide particles (emissions) and metal condensate penetrating the construction zone and owing to the use of recycled powder. The different mechanisms of contamination are established for the metal synthesized at high filling densities of the construction platform. A dense arrangement of samples and dominating exposure of the base metal result in better segregation of chromium oxides at the grain interfaces. A significant decrease in strength and ductility is obtained at a temperature of 1000°C after the second run. These parameters remain practically the same during further testing. The long-term strength slightly increases in the samples obtained in the second and the third run. The heat resistance of synthesized VZh159 alloy depends very little on the use of recycled powder. [ABSTRACT FROM AUTHOR]

Abstract—The changes in the microstructure during thermomechanical treatment under different regimes of a new granulated heat-resistant alloy based on VZh178P nickel obtained by the method of hot isostatic pressing and subsequent hot deformation (HIP + deformation) are studied. The change in the grain size of the γ matrix after the main operations of the technological conversion is shown; the dynamics of their growth in hardening below and above the temperature of total dissolution of the γ' phase and the microstructure after the total thermal treatment are shown. [ABSTRACT FROM AUTHOR]

The relationships between stresses and strains in metal porous composites manufactured using 3D technologies, as well as in dispersion-strengthened polymer composites with a hereditary relaxation or creep core, are considered. By applying the Volterra matching principle using the Laplace transform, the effective viscoelastic properties of the composite are calculated in the images. The originals of these characteristics were obtained by inverse transformations using the standard operational calculus method. For composites with a polymer matrix, the Yu.N. Rabotnov method of integral operators is used. As a result, effective stress relaxation characteristics were obtained for metal composites. For polymer composites, an effective law of creep under uniaxial loading was obtained. The theoretical results on creep were compared with similar experimental results. [ABSTRACT FROM AUTHOR]

There are high demands for the early and reliable detection of metal components used in safety-critical structures. Nondestructive testing (NDT) is a pivotal technique used across industries to assess a material's integrity without causing damage and has been used in early crack detection of metals, mainly based on changes in the crystal structure and magnetic properties of metals. This review provides an overview of internal and external detection technology based on nondestructive testing methods such as ultrasonic, electromagnetic, ray, magnetic particle, etc. Especially, the integration of advanced methodologies such as machine learning and artificial intelligence deserves a place in NDT methods. Furthermore, the multifactorial detection method is promoted to enhance the sensitivity and detection range due to advantage integration but still has emerging challenges for safer equipment and applications. The review aims to compare these methods and outline the future challenges of NDT technologies for metal crack detection. [ABSTRACT FROM AUTHOR]

At the Pervouralsk New Pipe Plant, in collaboration with the staff of the Ural Federal University, a technological scheme for the production of capillary tubes used for manufacturing disposable medical syringes was developed and implemented. To achieve the desired tube size, the tubes undergo drawing, followed by annealing in a continuous electric furnace with a protective atmosphere to relieve stress. To optimize the annealing process of the tubes, thermal losses were determined based on heat engineering calculations, which allowed for the optimization of furnace power. A calculation of heating elements was performed, determining the diameter and total length of the wire heaters. A method for calculating the heating time of thin bodies for capillary tubes of a given size was substantiated. Based on the constancy of the temperature in the furnace's working space and heat transfer primarily by radiation, the heating time for capillary tubes of different diameters was determined. When blowing tubes with various gases, pressure losses were calculated for tubes of different diameters and lengths. Temperature fields inside the muffles, through which the capillary tubes move, were investigated. The obtained results are of interest to technologists and can be useful in developing technological schemes for the production of capillary tubes for manufacturing medical needles. [ABSTRACT FROM AUTHOR]

A method is proposed to determine uncontrolled areas of aircraft engine parts in penetrant testing, taking into account the specifics of applying developers of different types (all forms according to ISO 3452-3). The main technological factors affecting the testability of surfaces of parts of complex geometry are presented. A method has been experimentally tested, which makes it possible to determine the uncontrolled zones of engine parts in penetrant testing, due to the specifics of applying different forms of developers. It has been established that when carrying out penetrant testing of parts, especially with complex configurations/geometry, the existing technologies for applying developers may not ensure its high-quality application to all controlled surfaces of parts, as was previously assumed based on the results of an expert assessment. It has been experimentally proven that such structural elements of parts as holes are controlled to a depth much less than the diameter. [ABSTRACT FROM AUTHOR]

In friction stir welding, the rotation of the tool at the joint between the metal plates causes frictional heating and metal plasticising. Processes of intense plastic deformation effect the formation of the weld microstructure, determining strength properties. However, the main factor is the specific temperature and time conditions under which the friction stir welding process is implemented. It has been established experimentally that when temperature-time parameters are violated, defects in the form of weld discontinuities are localized at the weld-base metal boundary, the formation of which is caused by the incompatibility of the weld metal deformation and the adjacent base material. It is shown that the mechanism of destruction of a welded joint is determined by the presence of defects reducing the effective cross-section of the welded joint. [ABSTRACT FROM AUTHOR]

Study of samples of three-layer material "chromium-containing steel Kh17N2/vanadium alloy/chromium-containing steel Kh17N2" obtained by laser growing is presented. The structural-phase state and strength properties of the vanadium alloy and three-layer alloy in the initial state, after heat treatment at 1200°C, and also after irradiation have been studied. The interaction zone of vanadium alloy and steel has been studied in detail. [ABSTRACT FROM AUTHOR]

High alloy nickel-based superalloys used for casting of single-crystal blades of aircraft gas turbine engines need to be subjected to a long high temperature homogenization annealing for dissolution of nonequilibrium γ' eutectics and for smoothing the dendritic segregation of alloying elements. Single-crystal nickel-based superalloy CMSX-10 of the third generation, which is developed by Cannon-Muskegon Corporation for casting highly loaded uncooled single-crystal blades of the first stage of the high pressure turbine of the Trent 800 aviation gas turbine engine, belongs to this class of alloys. In this study, the processes occurring during the high temperature homogenization annealing of this alloy are investigated. It is shown that the kinetics of dissolution of nonequilibrium γ' eutectics strongly depends on the temperature; namely, the dissolution rate in the range of 1340–1360°C increases by about an order of magnitude with an increase in the temperature by 10°C. The following two types of homogenization annealing with a stepwise increase in the temperature is proposed for CMSX-10 by Cannon-Muskegon: a long annealing for 45 h with ten steps of temperature increase and a shortened annealing for 20 h with six steps of temperature increase. The change in the solidus temperature of the alloy during the homogenization is studied by the method of electrical resistivity measurement. It is shown that both types the nonequilibrium eutectics are completely dissolved during homogenization annealing, and a longer annealing for 45 h ensures deeper chemical homogenization of the alloy. This is especially important for an alloying element, such as rhenium, which has a high segregation coefficient and very slow diffusion mobility in nickel. Deeper homogenization provides better thermal stability of the alloy microstructure and, consequently, higher long-term creep strength. A negative effect of high temperature homogenization is increased porosity resulting from the dissolution of γ' eutectics. Homogenization porosity can be reduced by optimizing the alloy composition and reducing the fraction of nonequilibrium γ' eutectics. [ABSTRACT FROM AUTHOR]

The most promising directions of the development of heat-resistant alloys (HRAs) based on refractory metals are analyzed. The microstructures characteristic of HRAs, which it is advisable to form in promising alloys, are considered. The stability factors of the microstructure with respect to the diffusion coarsening of the hardening phases are discussed. Two groups of alloys are considered as the most promising HRAs based on refractory metals. First, the principles for design of HRAs based on (Pt, Ir)-Sc with heterophase γ-γ' microstructure, where γ-matrix is a (Pt, Ir) solid solution with a FCC lattice, and γ' is a strengthening phase with the structure L12 by analogy with Ni-base superalloys, are developed. The resistance of γ-γ' microstructure in Ni, Pt and Ir alloys against the process of diffusion-limited coarsening is analyzed. It is shown that the diffusion permeability of Pt is several times less than that of Ni, so one should expect that Pt-based HRAs will not be inferior to Ni-based HRAs in terms of structural stability. The second group includes HRAs based on many not noble refractory metals. It is shown that solid solutions of the system (Ti, Zr, Hf, Ta, Nb) with a BCC lattice can be considered as a matrix of advanced refractory HRAs. The results of experimental studies of alloys based on (Ti, Zr, Hf, Ta, Nb) additionally alloyed with elements contributing to the formation of strengthening intermetallic and silicide phases are discussed. The issues of segregation of alloying elements at the grain boundaries of refractory alloys and the effect of segregation on the cohesive strength of the boundaries are considered. [ABSTRACT FROM AUTHOR]

The Ni-based superalloy is used as the turbine blade, which is subject to the coupling effect of temperature and super-gravity during service. As the Ni-based superalloys are difficult to become homogenous after using the solid solution heat treatment, a study on morphology and composition distribution of Ni-base superalloys with segregation during microstructural degradation is necessary. This study investigates the microstructure of the ex-service turbine blade and cast samples subjected to the high-temperature centrifugal test. The difference in the size and shape factor of the γ′ phase decreased with the stress caused by the super-gravity condition, indicating a higher magnitude of homogenization degree. The higher stress will also promote the merge of the sub-grain boundaries, leading to a lower density and higher orientational deviation of the sub-grain boundaries. [ABSTRACT FROM AUTHOR]

Using the method of directional solidification, single crystals of experimental nickel-based superalloys with negative, zero, and positive γ/γ' misfits are obtained. The γ' solvus, solidus, and liquidus temperatures of the alloys are determined, and the microstructures of the alloys after directional solidification, heat treatment, and creep tests are investigated. Creep tests are performed at temperatures of 800 and 1000°C. It is found that single crystals of the alloy with a negative γ/γ' misfit have the highest creep resistance and lifetime (the crystal lattice period of the γ' phase is smaller than that of the γ matrix). [ABSTRACT FROM AUTHOR]

Technological capabilities for casting of long turbine blades with an axially oriented single-crystal structure 〈001〉 produced from low-density superalloy are explored. The principles of designing starting cavities for single-crystal casting of blades are considered. The produced structures of model blocks for long blades with selected parameters of superalloy casting at the UVNK-type production unit for directional solidification equipped with an automated control system for the casting process (G = 60–80°/cm) make it possible to fabricate the blades with single-crystal structure throughout the height. The major physicomechanical properties of the alloy with crystallographic orientation (CGO) 〈001〉 are provided. The results of studying the characteristics of the single-crystal as-cast structures of long blades made of Ni-based superalloy are presented: the quantification of the microstructure, the data on the structure-phase characteristics of material in single-crystal blades after casting, and the data of electron-probe microanalysis. [ABSTRACT FROM AUTHOR]

Reference X-ray images of defects in castings and welded joints have been used for many years in X-ray radiation inspection. With the transition to digital technologies and the use of flat-panel detectors instead of radiographic film, the problem arose of creating reference digital images. Comparison of the digital image of the reference sample with the digital image of the test object can be carried out using software, which completely or partially excludes the subjective assessment of the operator and makes it possible to view doubtful areas of the image with magnification and without loss of contrast, automatically showing the size of the defect and its intensity distribution by volume of the casting. All this makes the control more objective and productive. The reference images in the detector's memory do not undergo the aging and degradation typical of X-ray images, and there is no need to replicate them. [ABSTRACT FROM AUTHOR]

This article investigates the change in the structure of heat-resistant nickel alloys doped with cobalt, chromium, molybdenum, aluminum, niobium, tungsten, and titanium and aluminum, cobalt, rhenium, tantalum, ruthenium, molybdenum, tungsten, and chromium under the influence of a solution of 75%Na2SO4 + 25%NaCl in temperature range 600–750°C. As the results of the study show, a corrosive film of a layer structure based on oxides of chromium, aluminum, nickel and nickel sulfides is formed on the metal surface. It has been established that the nature of corrosion destruction of metal depends on the composition and content of alloying elements in it. [ABSTRACT FROM AUTHOR]

The problem of obtaining priming materials from Ni–W alloys arose in connection with the development of technology for casting single-crystal turbine blades of gas turbine engines (GTE) from high-temperature alloys. This technology uses a seed method for producing single-crystal castings with a crystallographic orientation [001] using seedings from alloys of the Ni–W system with a melting point 120–140°C higher than the casting alloy. The use of such primers greatly simplifies the casting process of turbine blades with a single-crystal structure, increases its reliability both in pass-through furnaces of the PMP-2 type and in high-gradient furnaces of the UVNK-9A type. The article presents the results of the study of the influence of temperature–velocity parameters of directional crystallization, namely, the temperature gradient GZ on the structure of the obtained single-crystal seed blanks, as well as the study of effects of tungsten and carbon on the structure of single-crystal seed blanks, and makes recommendations for optimizing the technological process of single-crystal casting of Ni–W seed blanks adjusting the alloy composition for the seed blanks. [ABSTRACT FROM AUTHOR]

The thermophysical and physicochemical properties of KMKS-3m.150.T10.37 prepreg and a fiberglass on its basis were investigated. Using multivariate regression methods, the prepreg curing process was studied. It was shown that the experimental dependences can be most adequately described by nth order differential equations for the consumption of the components with auto-acceleration in a three-stage process. Based on the results of the kinetic analysis, the rates of heat generation during prepreg curing in two-stage temperature-time regimes were predicted. Additional heat treatment at a temperature of 150°C afforded a 16°C decrease in the internal temperature (self-heating) of the material. The finite element method was used to calculate the temperature field during the material molding. It was demonstrated that, using the model proposed, the temperature field characteristics can be determined accurately to within 3%. Examination of the distribution of the glass transition temperature of the fiberglass over the volume of the product showed that the difference between the maximum and minimum temperatures may reach 35°C. [ABSTRACT FROM AUTHOR]

A nickel-based eutectic alloy with a γ/γ '-NbC structure was directionally solidified with a planar front. The specimens were tested for creep under sawtooth thermal cycling in the temperature range from 600 to 1100°C. It has been established that the lifetime under the conditions of thermal cycling is about five times shorter than it is predicted by the linear damage accumulation rule on the basis of results of isothermal creep tests. Faster creep under thermal cycling is caused by the rapid coarsening of the γ/γ ' microstructure due to the periodic partial dissolution and reprecipitation of the γ ' phase in heating and cooling half-cycles. [ABSTRACT FROM AUTHOR]

In this paper, results of the study of the microstructure of a VZhL939 corrosion-resistant heat-resistant nickel alloy (HNA) at different stages of post-processing are described. More specifically, the morphology of the particles of the γ' phase and carbides after selective laser melting, hot isostatic pressing, thermal treatment, and long-term strength tests is studied. Allowable preferences of short-term mechanical characteristics and long-term strength of this alloy as compared to the EP648 and VZh159 alloys produced through selective laser melting are given. [ABSTRACT FROM AUTHOR]

Attention focuses on how the parameters used in selective laser fusion of metal powder and cold isostatic pressing of heat-resistant high-chromium alloys affect the final microstructure and the number and size of the pores formed. The cold isostatic pressing of alloys produced by selective laser fusion decreases the number and size of the pores. Deformation at normal temperature increases the hardness of the alloys. [ABSTRACT FROM AUTHOR]

Using the method of high-temperature chemical synthesis, material samples with a high-temperature protection system were fabricated. The study of the thermochemical effect of high-enthalpy air flows on a carbon-containing composite material with a high-temperature antioxidant coating based on hafnium compounds at surface temperatures of 1400–1600°C was carried out in a free subsonic jet of high-enthalpy air of a VGU-4 100-kilowatt high-frequency induction plasma torch. The experiments were carried out at a pressure of 100 hPa in a stepwise heating mode and in a constant surface temperature mode of 1400, 1500, and 1600°C. The duration of each test cycle in the constant temperature mode was 1500 s. [ABSTRACT FROM AUTHOR]

By means of the X-ray microspectral analysis and scanning and transmission electron microscopy, we investigate the composition of hardening phase particles—nitrides—after internal nitriding and subsequent heat treatment in the Ni–Co–Cr–W–Ti system of grade VZh171. The particles differ significantly in chemical composition: the main forming element—titanium or chromium—is proportionally replaced by the other alloy components. The nitride compositions at the surface and in the center of the sample differ in the element ratio. After annealing in vacuum, the content of chromium, tungsten, and cobalt in nitrides decreases, also less becomes the difference in the precipitate composition in the surface and the central layers of the sample; this phenomenon can be used to improve the alloy properties. [ABSTRACT FROM AUTHOR]

In this paper, we study the welded joints of cast intermetallic single-crystal rhenium-containing alloy VKNA-25 with crystallographic orientation [001] and deformable disk heat-resistant nickel alloy EP975 depending on the parameters (temperature and degree of deformation) of pressure welding under superplasticity conditions. The samples before and after heat treatment (annealing at 1210°C for 5 h) are compared. The results of X-ray spectral microanalysis of a solid-phase joint in the welding zone and at distances of up to 140 μm are presented in comparison with the initial chemical composition of the alloys, indicating an intense course of diffusion processes. The obtained results are analyzed from the point of view of maintaining the balance of alloying that is calculated by the method of G.I. Morozova (calculating the number of valence electrons per unit atomic mass of the composition). The change in the atomic mass and average electron concentration of solid-phase compounds before and after heat treatment in the welded joint zone and at distances of up to 140 μm is calculated. Calculated with allowance for the alloying balance, the alloy compositions are shown to allow obtaining a high-quality one-piece connection of a disk and a blade for blisk-type structures that is performed under superplasticity conditions using a setup for high-temperature pressure welding. [ABSTRACT FROM AUTHOR]

We investigate the influence of the heat treatment regimes on corrosion resistance and strength properties of precipitation-hardening EP718 nickel-based alloy initially developed for the aviation industry conditions and currently used in the oil and gas industry. Here considered is the effect of the hardening temperature (980–1130°С) and the holding time (1–2 h), as well as of the intermediate and final aging stages duration (4–20 h) at the temperatures of 780 and 650°С. We state that the strength and the corrosion properties of the EP718 alloy are governed by the hardening temperature. At its value of 980°C, the highest strength characteristics are achieved (the yield point being σy = 950 MPa) due to the higher grain score equal to 3.5, and to the presence of the various size inclusions (their volume fraction being 0.61%); yet, in that case, the corrosion rate reaches V = 5.88 g/(m2 h). At the temperature of 1130°C, the best corrosion characteristics are observed (V = 2.04 g/(m2 h)) due to the detrimental phase dissolution (the volume fraction of non-metallic inclusions being 0.47%); yet, the strength properties decrease (σT = 756 MPa) because of the lower grain score – 2.7. The ageing regime consisting of the intermediate stage with the holding at t = 780°С for 5 h and the final stage at 650°С, τ = 16 h, with cooling in air, leads to the maximal hardening: to the hardness increase up to 37.5–38.5 HRC. By means of the electrochemical studies we show that the ageing duration increase leads to a decrease in the passive state stability. [ABSTRACT FROM AUTHOR]

The temperature dependences of the periods of the crystal lattices of the γ and γ' phases, their dimensional mismatch (misfit), and volume fraction of the γ' phase of an experimental single-crystal high-temperature nickel-based alloy have been determined by X-ray diffraction analysis in the temperature range of 18–1150°C. The temperature ranges in which intense changes in the structural and phase characteristics of the alloy under study take place have been determined. [ABSTRACT FROM AUTHOR]

Critical values of the Niyama criterion were determined for castings from alloy ML10 on the basis of a computational experiment. It was shown that the Niyama criterion is suitable only for qualitative evaluation of the possibility of porosity formation. One of the options of constructing an unambiguous dependence and scale of porosity by the values of the temperature gradient and solidification rate was proposed. [ABSTRACT FROM AUTHOR]

An analytical model for forecasting the temperature dependence of γ/γ' misfit in heat-resistant nickel alloys is proposed. The model accounts for the concentration dependences of the periods of crystalline lattices of the γ and γ' phases (Vegard law), thermal expansion of the γ and γ' lattices, and dissolution of the γ' phase at high temperatures. Adequacy of calculations of misfit is confirmed by comparison with the results of measurements using methods of X-ray and neutron diffraction. The model is applied for development of a nickel alloy with positive misfit. [ABSTRACT FROM AUTHOR]

We performed high-temperature treatment of the Ni–C, Al–C, and Ni–Al–C powder mixtures (5 wt % C (soot)) up to the melting point of the respective metals and found that the melt particles coagulate with formation of Ni, Al, and NiAl (intermetallic) spherical particles, respectively. The Ni particles have almost perfect spherical shape and a multilayer graphite coating. The NiAl particles have a thin graphene (graphite) coating. [ABSTRACT FROM AUTHOR]

A comprehensive approach is proposed for evaluating the effectiveness of various sources of ultraviolet radiation used in the fluorescent penetrant method of nondestructive testing. The spectral characteristics of the radiation of modern domestic and foreign UV irradiators used in the testing of parts and assemblies of aviation equipment in the aviation industry are given. The main parameters that allow the most complete assessment of ultraviolet sources for compliance with the requirements of domestic and foreign regulatory documents on the energy characteristics of sources at the stage of inspection of the technological process of capillary control are determined. The influence of the use of UV sources of various types on the results of testing samples and parts with different design features containing manufacturing and operational defects of various sizes is shown. It has been established that the characteristics specified in their technical documentation (passports) are not sufficient for a flaw detector operator to evaluate various UV irradiators. This approach will allow one to evaluate and select modern sources of UV radiation, taking into account the requirements of standards in force at enterprises. [ABSTRACT FROM AUTHOR]

Centrifugal SHS casting has been used for the production of NiAl–Cr–Co–X alloys, where X = 2.5–15.0 wt % Mo and up to 1.5 wt % Re. The influence of modifying additives on burning has been studied, as well as on the phase composition, structure, and properties of cast alloys. The addition of up to 15% Mo and 1.5% Re in terms of all properties makes the highest improvement of the properties with regard to basic alloy. Molybdenum, while forming the plastic matrix, improves strength properties up to the following levels: uniaxial compressive strength σucs = 1730 ± 30 MPa, yield strength σys = 1560 ± 30 MPa, and plastic deformation constituent εpd = 0.95%; annealing at t = 1250°C improves them to σucs = 1910 ± 80 MPa, σys = 1650 ± 80 MPa, and εpd = 2.01%. Rhenium modifies the alloy structure and improves its properties to σu = 1800 ± 30 MPa, σys = 1610 ± 30 MPa, and εpd = 1.10%, whereas annealing improves them to σucs = 2260 ± 30 MPa, σys = 1730 ± 30 MPa, and εpd = 6.15%. Using the nanoindentation method, the mechanical properties of NiAl, (Ni,Cr,Co)3MO3C, Ni3Al, (Cr,Mo), and MoRe2 phases, as well as of Al(Re, Ni)3 hypothetic phase have been determined. It has been demonstrated that local softening upon annealing from t > 850°C improves the portion of plastic deformation upon compression tests, which is related with the loss of coherency of boundaries of nanosized disk deposits on the Cr base with an oversaturated solid solution similar to the Guinier–Preston structural transformation. The three-level hierarchical structure of the NiAl–Cr–Co–15% Mo alloy has been established: the first level is formed by β-NiAl dendritic grains with interlayers of (Ni,Co,Cr)3Mo3C and (Mo0.8Cr0.2)xBy molybdenum containing phases with cell sizes up to 50 μm, the second level is comprised of Cr(Mo) strengthening submicron particles distributed along the grain boundaries, and the third level is comprised of coherent Cr(Mo) nano deposits (10–40 nm) in the body of β-NiAl dendrites. Using procedures of mechanical grinding of the cast alloy, a powdered precursor has been obtained with an average particle size of Davg = 33.9 μm for subsequent spheroidization. [ABSTRACT FROM AUTHOR]

This article analyzes the chemical composition, structure, and mechanical properties of heat resistant nickel alloy, grade EP648, fabricated by various methods: deformation, lost wax casting, and selective laser sintering. It has been demonstrated that the deformed material is characterized by low porosity and higher impact toughness and plasticity; the cast material is characterized by coarser grains and a high level of long term strength and low cycle fatigue; and the material fabricated by selective laser sintering is characterized by a higher content of oxygen and nitrogen and a fine-grained structure with extremely intense grain irregularity and inheritance, as well as higher short term strength. [ABSTRACT FROM AUTHOR]

The results of testing for the FCGR (fatigue crack growth rate) in compact samples upon eccentric tension using a crack opening displacement (COD) under the conditions of an asymmetric loading cycle (R = 0.1) at a room and elevated temperature are presented. The relationship between the conditions of force loading and the conditions of preliminary initial fatigue crack growth is considered. The values of effective stress intensity factor Keff have been obtained, being an important estimate for the interpretation of observed crack growth features. The properties of the cyclic crack resistance of the VZh175-ID alloy are compared with the properties of such foreign analogs as Rene 88DT and Inconel 625 SLM and such domestic analogs as EP741NP and EK151-ID. The effect of testing temperature on the growth rate is demonstrated. The hypothesis of the linear dependence of the parameters of the Paris equation has been verified. [ABSTRACT FROM AUTHOR]

An analysis of the influence of the ratio of alloying elements in the Ni–Al–Cr–W–Mo–Ta system on the resistance of the deposited metal to thermal fatigue is presented. The cumulative effect of alloying elements on the resistance of the deposited metal to the appearance of cracks in conditions of cyclic temperature changes in the range of 20–1150°C has been established. It is shown that, in the alloying system under consideration, the sensitivity of the metal to the formation of thermal fatigue cracks mainly depends on the amount of refractory elements that cause the formation of topologically close-packed (TCP) phases. The content in the deposited metal of 3.5 wt % tungsten, 3.0 wt % molybdenum, and 2.5 wt % tantalum does not cause fatigue cracks. The developed type of deposited metal provides a high level of thermal and oxidative wear resistance as compared to high-alloyed industrial nickel and cobalt alloys. [ABSTRACT FROM AUTHOR]

The sulfuric-acid leaching kinetics of nickel as the main component of grinding wastes originating from machining a rhenium-containing heat-resistant ZhS-32VI superalloy and containing the impurities of abrasive materials, oils, ceramics and other pollutants has been studied in the agitation mode concentrating refractory metals in the solid residue. The nickel content amounts to 60% and, alongside nickel, there are other metals in the grinding wastes, including rhenium, chromium, cobalt, tungsten, tantalum, molybdenum, hafnium, titanium, and aluminum. The leaching of nickel from wastes with the use of a sulfuric acid solution has been carried out using a thermostated cell at an elevated temperature (55–85°С), the ratio between the wastes and the solution of sulfuric acid (3 M) amounting to 1 : 10 g/mL and the stirring rate being of 200 min–1. To study the kinetics, a grinding waste fraction (–0.071 mm) obtained with the greatest yield (49.2 wt %) has been used. Convex kinetic curves of nickel leaching from the wastes have been obtained. It has been revealed that, when the temperature changes from 55 to 85°С, the time until the leaching stops decreases from 220 to 140 min, and the level of nickel extraction from the solution increases from 45 to 99%. The kinetic curves are linearized according to shrinking sphere, Gistling–Braunstein and Kazeev–Erofeev equations. The latter has turned to be most suitable for describing the process. Taking into account the assessment of the correlation coefficients of the mentioned anamorphoses, it has been found that the leaching of nickel from the grinding wastes is rate-determined by a chemical reaction, and the process occurs in a kinetic mode. The apparent activation energy Eact, calculated using the Arrhenius equation, and the rate constants, obtained via processing linearized kinetic curves according to the shrinking sphere model, amounts to 47.5 ± 0.5 kJ/mol. This value confirms the fact that the leaching process occurs in a kinetic mode and can be intensified via increasing the reaction temperature. [ABSTRACT FROM AUTHOR]

Upsetting tests of VTI-4 alloy samples at a temperature of 1010°C under high-rate loading have been carried out. On the basis of the test results, the elastic modulus, as well as the level of axial and radial plastic strain within the end zone and within the central zone at each stage of loading, has been determined. Criteria are proposed for the correspondence between finite element simulation and experimental data, and a model diagram is plotted for the deformation of the VTI-4 alloy at a temperature of 1010°C and a deformation rate of 2.5 s–1. As a result of the simulation, a relationship between the material structure obtained during high-rate upsetting and the stress-strain state within different zones has been determined. [ABSTRACT FROM AUTHOR]

The review article is devoted to high-temperature borosilicate molybdenum alloys reinforced with titanium carbides MoSiBTiC. The article discusses phase diagrams, microstructure, production methods, mechanical properties, resistance to oxidation of these alloys, and protective coatings. It is shown that the long-term strength of MoSiBTiC alloys is superior at high temperatures to nickel heat-resistant alloys (NHRA) of the latest generations. Borosilicate molybdenum alloys MoSiBTiC can replace nickel heat-resistant alloys in many engineering fields, including in the production of cast parts for the hot section of aircraft gas turbine engines. [ABSTRACT FROM AUTHOR]

A brief review of studies of the extraction-pyrolytic method to produce inorganic materials of various purposes is presented. The potential to use products of the extraction-pyrolytic method as precursors in additive manufacturing is discussed. Modern methods of 3D printing using powder materials are considered. A process flow diagram is proposed for an extraction-additive technology (from raw material to articles). [ABSTRACT FROM AUTHOR]

Interaction of Ti–C with titanium alloys of α + β and pseudo α classes and formation of the reaction layer at the interface have been investigated. We used titanium α + β alloys VT6 (Ti–Al–V) and VT8 (Ti–Al–Mo–Si) as well as pseudo α alloy VT20 (Ti–Al–Zr–Mo–V). The structure and composition of the interfaces were investigated by means of TEM in the scanning beam mode and energy dispersive spectroscopy. It was ascertained that, already at the stage of production of the samples by thermal diffusion joining, interphase chemical interaction and formation of the reaction layers occurred. The reaction layer consists of distinct regions of small crystals (nanocrystals of TiC of 10–50 nm in size) and large grains of Ti8C5 100–500 nm in size. Most of the reaction layer consists of large grains of Ti8C5. It is found that the average thickness of the reaction layer varies depending on the Ti alloy type and is ~0.89 μm (VT6 alloy), ~0.97 μm (VT8 alloy), and ~0.51 μm (VT20 alloy). Additional heat treatment of the samples leads to increasing thickness of the reaction layer in all Ti–C/Ti alloy systems due to the growth of large grains of titanium carbide. [ABSTRACT FROM AUTHOR]

The technology of obtaining composite material experimental samples based on an intermetallic alloy of VKNA type reinforced with oxide particles in an amount of 2–5 vol % is presented. An intermetallic VKNA-1V alloy containing 80–90 wt % of γ' phase was used as the matrix prototype. Al2O3 particles, as well as complex oxides AI2O3⋅Y2O3, AI2O3⋅Y2O3⋅HfO2, were used as reinforcing particles. Granules of VKNA-1V alloy were obtained by gas atomization at the Hermiga Gas Atomiser. Subsequently, these granules were subjected to mechanical alloying with the aim of introducing particles of the aforementioned compositions of oxides to form a composite mixture corresponding in composition to the desired composite material. Experimental composite material samples with different contents of reinforcing particles were obtained from powder mixtures by spark plasma sintering (SPS) with further hot isostatic pressing (HIP). To study the microstructure of experimental samples, the method of scanning electron microscopy was used. Time to failure of experimental samples sintered by spark plasma combined with HIP was determined at a temperature of 900°С and stress of 50, 45, and 35 MPa. It is shown that to determine the areas of application of the developed composition, the hot isostatic pressing operation is necessary, but not sufficient. [ABSTRACT FROM AUTHOR]

The influence of REEs, for example, Sc and Nd, on the structural phase state and behavior at oxidation in a dry and humid atmosphere of hypoeutectic high-temperature composite Mo–Si, crystallization of which from melt proceeds with formation of a two-phase in situ composite, was investigated. Samples of the model alloys with different concentration of REE were formed by vacuum arc melting of the charge material consisting of the binary alloy Mo–15 Si (at %) and additions of the doping elements. According to the data of X-ray diffraction and electron microscopy, the phase composition was determined, the peculiarities of the microstructure and pattern of distribution of alloying constituents in metal silicide composites Mo–Mo3Si containing from 0.5 to 3.0 at % Sc or Nd were revealed. The corrosion resistance of alloys Mo–15 at % Si–REE (Sc, Nd) at continuous heating to 700 and 850°C in air and in an air-vapor medium was estimated by the methods of thermal analysis (differential scanning calorimetry (DSC) and differential thermal analysis (DTA)). It was demonstrated that microalloying of the Mo–15 at % Si alloy with scandium or neodymium within the limits of 0.5 at % results in decrease of the oxidation rate at heating in air to 850°C. Increase in the concentration of doping elements to 3.0 at % REE at oxidation in air adversely affects the corrosion resistance of the samples; at the same time, oxidation of the alloys with neodymium proceeds at a higher rate than that with scandium. In an air-vapor medium, at nonisothermal heating, the alloy doped with scandium is oxidized more slowly than the binary alloy, while the sample with neodymium, on the contrary, is oxidized at a much greater rate in comparison with dry air. [ABSTRACT FROM AUTHOR]

By means of X-ray phase analysis and energy-dispersive X-ray analysis, the effect of yttrium on the structural-phase state of the hypoeutectic Mo–15.3 V–10.5 Si alloy is investigated. It is established that the main phases of the Мо–(15.4–14.3) V–(10.6–9.8) Si–(0.3–5.3) Y alloys obtained under the conditions of nonequilibrium solidification are the (Mo1 –xVx)ss metal solid solution (matrix), (Mo1 –xVx)3Si silicide solid solution, and Y5Si3 silicide. In alloys doped with yttrium up to 1.0 at %, the space between dendrites of the (Mo1 –xVx)ss metal phase is filled with the (Mo1 –xVx)3Si solid solution, and at the boundaries of the metal solid solution, Y5Si3 is located. At the yttrium concentration of alloys higher than 3.0 at %, space between the (Mo1 –xVx)ss dendrites is filled with Y5Si3 silicide, inside which (Mo1 –xVx)3Si grains are formed. No ternary and quaternary yttrium-containing compounds are detected. The elemental composition of phases of the Мо–(15.4–14.3) V–(10.6–9.8) Si–(0.3–5.3) Y alloys is almost identical and is characterized by silicon nonstoichiometry. The silicon content of the (Mo1 –xVx)ss and (Mo1 –xVx)3Si phases lies within the accepted limits of the homogeneity region, and the silicon concentration of Y5Si3 (≈35.4 at %) goes beyond the defined limits. Doping the Мо–15.3 V–10.5 Si alloy with yttrium increases the degree of dispersion of the structure. Particles of the main structural constituents become close in size. At the same time, the volumetric ratio of the metal phase to the silicide phase increases as the yttrium content of the alloys is raised. The density of the alloys varies within 8.7 and 9.0 g/cm3. [ABSTRACT FROM AUTHOR]

The form of fatigue failure of single crystals of experimental nickel superalloy with 〈001〉 and 〈111〉 axial CGOs is studied using the fractographic method. The fracture surface of the single-crystal alloy specimens possesses a complex spatial texture. Fracture along cleavage faces of various sizes is observed. [ABSTRACT FROM AUTHOR]

The features of deformation of high-alloy heat-resistant nickel alloys for disks of gas turbine engines of the Ni–Co–Cr–W–Al–Nb–Ti–Mo system (EP962, EK151, and EP975 type) have been studied near the temperature of complete dissolution of the strengthening γ' phase. Analysis of the deformation curves has shown that the softening processes are controlled by dynamic recrystallization, and the greatest decrease in the flow stress in the two-phase region is observed at a temperature of ~20°C below the complete dissolution of the γ' phase, which is associated with the presence of ~10% of γ' particles larger than 1.5 μm. [ABSTRACT FROM AUTHOR]