Систематизированы экспериментальные результаты исследований микроструктуры жаропрочных никелевых сплавов, полученных методом селективного лазерного сплавления при различных условиях кристаллизации. Изучена дендритная (ячеистая) структура и распределение легирующих элементов в объеме ветвей дендритов методами растровой и просвечивающей электронной микроскопии. Показано, что выявленная микроликвация соответствует нормальному закону кристаллизации и обусловлена концентрационным переохлаждением. Установлено, что основными факторами формирования тонкой структуры трека являются ориентированное нарастание (эпитаксия) и конкурентный рост кристаллитов. При этом передача ориентации кристаллитов осуществляется осями не только первого, но и второго порядков, а конкретное направление реализуется при совпадении кристаллографической ориентации кристаллита с радиальным направлением теплоотвода. Усложнение тонкой структуры и ее фрагментация связаны с механизмом стохастической бинаризации кристаллографической ориентации, реализующимся при частичном переплаве и вскрытии фрагментов ячеек текущего и предыдущего слоев.

Experimental results of microstructural studies of refractory nickel alloys obtained by selective laser melting under different crystallization conditions are systematized. The dendritic (cellular) structure and the distribution of the alloying elements in the volume of dendrite arms are studied by scanning and transmission electron microscopy. The detected microsegregation matches a normal crystallization law and is caused by concentration supercooling. It is shown that the main factors responsible for formation of the fine structure of a track are the orientation growth (epitaxy) and the competitive growth of crystallites. The orientation of the crystallites is transferred not only by the first-order arms but also by the second-order arms, and a specific direction is implemented upon coincidence of the crystallographic orientation of the crystallite with the radial direction of the heat removal. The increasing complexity and the fragmentation of the fine structure are associated with the mechanism of stochastic binarization of the crystallographic orientation implemented upon partial remelting and opening of fragments of cells in the current and preceding layers.

The main results of the works of FGUP VIAM carried out within the framework of the program for the creation and adaptation of materials for the SLM technology are presented. The problems arising during the conversion of traditional alloys to additive manufacturing and related to the optimization of chemical composition and heat treatment conditions are considered. The directions and results of creating SLM materials, in particular aluminum- and iron-based alloys, are discussed. Such materials are compared with analogs produced by traditional technologies.

Results of structural studies of aluminum alloys of the Al – Si – Mg – (Cu) system obtained by selective laser melting are analyzed and systematized. The effect of heat treatment on the structural and phase condition of the alloys is investigated with the use of thermodynamic simulation and transmission electron microscopy. Comparative analysis of mechanical properties of the alloys in different states provided by different heat treatments is performed.

The works performed in FGUP VIAM to develop high-temperature cobalt- and nickel-based materials for the SLM technology are reviewed. They are compared with foreign analogs in terms of application and with the materials produced by traditional technologies. Promising works in the field of synthesizing high-temperature and intermetallic materials with a given texture are described.

RATIONALE:The Sm2 O3 -ZrO2 -HfO2 system is a promising base for the development of a wide spectrum of new refractory materials. Reliable data on thermodynamic properties in this system are of significant importance for planning the preparation and application of high-temperature ceramics. Especially, they can be useful for calculation of the unknown phase equilibria in this system. METHODS:The thermodynamic properties of the Sm2 O3 -ZrO2 -HfO2 system were studied by the high-temperature mass spectrometric method. The samples in the system under consideration synthesized by the solid-state method were vaporized from a tungsten twin effusion cell using a MS-1301 magnetic sector mass spectrometer. Ionization of the vapor species effusing from the cell was carried out by electrons at an energy of 25 eV. RESULTS:It was shown that, at temperatures below 2500 K, the main vapor species over the ceramics based on the Sm2 O3 -ZrO2 -HfO2 system were SmO, Sm, and O corresponding to vapor composition over pure Sm2 O3 . The SmO, Sm, and O partial vapor pressures over the samples and the Sm2 O3 activities were obtained in the temperature range 2319-2530 K. This allowed the excess Gibbs energy values to be determined. For comparison, the excess Gibbs energies in the Sm2 O3 -ZrO2 -HfO2 system were also calculated by the semi-empirical Kohler, Toop, Redlich-Kister, and Wilson methods and optimized by the statistical thermodynamic Generalized Lattice Theory of Associated Solutions (GLTAS). CONCLUSIONS:The thermodynamic data calculated by the semi-empirical approaches at 2423 K were shown to be lower than the experimental values. However, the Toop and Wilson methods were found to be useful for evaluation of the excess Gibbs energy values at the Sm2 O3 mole fraction less and higher than 0.32, respectively. The self-consistent thermodynamic description of the Sm2 O3 -ZrO2 -HfO2 system was derived at high temperatures by optimization of the experimental results using the GLTAS.

The main stages of the development of selective laser synthesis of resource parts, including the stages of melting a charge blank, production of metallic powder compositions, physicomechanical treatment of powders, and development of exposure conditions for a base metal and surface elements, are reviewed.

The article presents the results of a study of the behavior of a composite material, a matrix based on an organic polymer filled with fibers of partially stabilized zirconium dioxide, under exposure to air at temperatures above 2000°C. The discovered phase and structural changes lead to the formation of a new, low-temperature phase, while the fibrous structure of the material was maintained. The study makes it possible to evaluate the use of a composite material with an organic matrix reinforced with refractory zirconium oxide fibers under conditions of short-term exposure to extremely high temperatures.

Thermodynamic properties and vaporization processes of the Gd2O3-HfO2 and Gd2O3-ZrO2 systems were studied by the Knudsen effusion mass spectrometric method (KEMS). The samples used in the present study were synthesized by sintering of pure oxides. The vapor species over the systems at the temperature 2600 K were GdO, ZrO, HfO, ZrO2, and atomic oxygen. The partial pressures of the vapor species, the component activities, and the excess Gibbs energies were obtained in the binary systems studied. It was illustrated that thermodynamic properties found in both systems had the negative deviations from ideality. The thermodynamic data found in the present study were also discussed using the results of modeling of the component activities based on the generalized lattice theory of associated solutions. Correlations were shown between the observed changes in the thermodynamic behavior of the Gd2O3-HfO2 and Gd2O3-HfO2 systems and the relative number of bonds formed in the condensed phase when the second coordination sphere was taken into consideration. (C) 2022 Elsevier B.V. All rights reserved.

New models of competitive aviation and space technology cannot be created without contemporary materials. The development of aluminum–lithium alloys was mainly determined by the fact that the addition of lithium to aluminum alloys decreases their density and increases the modulus of elasticity, thereby providing a significant structural weight reduction compared to traditional aluminum alloys. Along with a reduced density, aluminum–lithium alloys have high strength, good corrosion resistance, and good weldability; therefore, they represent a strategically crucial material for aviation and space technology products. This article presents the history of the development of aluminum–lithium alloys and their application.

The structure and characteristics of EP648 and VZh159 heat-resistant alloys synthesized by selective laser melting after HIP, aging, and simulated annealing for 500 h are compared. The disbalance of alloying of EP648 and VZh159 alloys is calculated. It is shown that a decrease in strength characteristics, an increase in ductility, and a decrease in the period between simulated annealing and fracture of EP648 alloy is related to a decrease in the volume fraction of the particles of the σ phase caused by precipitation of α-Cr particles. It is determined that the synthesized VZh159 alloy after simulated annealing is far superior to the EP648 alloy according to the set of mechanical characteristics owing to more balanced alloying.

We perform investigations aimed at the development of the main technological parameters of melting of high-chromium corrosion-resistant refractory nickel alloys in vacuum induction furnaces. We study the problems of refining of these alloys with removal of admixtures and gases in the course of melting in vacuum induction furnaces with crucibles whose mass does not exceed 1000 kg and also of their microalloying with rare-earth metals and, in particular, with lanthanum. We determined the influence of size of melting crucible and the angle of its inclination on the efficiency of refining of the melt. Finally, we compared the quality of the metal melted according to the developed parameters with a similar metal supplied from abroad.

The paper reviews the results of development of a new class of high-temperature composites based on niobium and various types of reinforcers continuous monocrystalline fibers (MCF) α-Al2O3, with TiN, Mo, W barrier coatings, and with controlled (Si, Ti) and uncontrolled (O, C) impurities. The analysis of Nb–Si, Nb–C, Nb–O binary diagrams and Nb–Si–Ti, Nb–Fe–Ti ternary diagrams was performed, on the basis of which the matrix compositions were selected. The basis for the preparation of composites was the powder method of mechanical alloying of the mixture preparing, followed by its pressing together with α-Al2O3 MCF by spark plasma sintering (SPS) and further preparation of experimental samples. An analysis of the interaction of fibers with a matrix was carried out, where the matrix was Nb or system on the basis of the above mentioned binary or ternary diagrams.

The formation of internal stresses in polymer composite materials (PCMs) caused by different elastic moduli and thermal expansion coefficients of polymer resin and reinforcing fibers, as well as by swelling due to the moisture uptake is discussed. The influence of thermal cycles on the internal stresses and strength of the materials was studied in dry and wet atmospheres. It shown that thermal cycles cause a periodic jumps in the stresses at lowfrequency mechanical loadings, during which the mechanical properties are degraded due to the formation of microscopic cracks in the polymer matrix. The relative changes in the strength, elastic modulus, glass-transition temperatures, moisture diffusion coefficient, and other PCM physical characteristics are proportional to the logarithm of the number of cycles and also depend on the form and size of specimens, amplitude, conditions, and length of thermal cycles. A prolonged action of external actions relaxes the internal stresses and reduces their influence on the aging of PCMs.

The results of the study of a complex of properties and structure of the experimental samples of fiberglass plastics with an internal vibration absorbing layer are given. It was found that the introduction of a vibration absorbing layer into the internal structure of a laminated plastic leads to an increase in its vibration damping properties but impairs the mechanical characteristics. The causes of the decrease of the strength properties of a polymer composite material after the introduction of the internal vibration absorbing layer into its structure were examined.

The evolution of the structural-phase state of the VZh159 alloy fabricated by selective laser melting after various types of thermal exposure and hot isostatic pressing (HIP) is studied. The effect of a long 500-h exposure at temperatures of 800 and 900°C on the phase composition and morphology of structural components is determined. The short-term and long-term strength of the material in various conditions are studied. It is shown that the segregation of dispersed particles of the σ phase after the gas-static treatment followed by aging and after prolonged exposure at high temperatures does not have a significant negative effect on the plastic and strength characteristics of the alloy. The long-term strength of the synthesized metal after the 500-h exposure at a temperature of 900°C corresponds to the certified values ​​for the deformed semifinished product of the VZh159 alloy.

Composite rebar is a promising building material due to its advantages over steel rebar. Polymer reinforcement consists of a hardened matrix reinforced with a continuous fiber. The main role of the matrix is to determine the performance properties of the composite and to distribute stresses in the reinforcing filler. Optimization of the polymer matrix composition in terms of strength and technical parameters makes it possible to obtain a composite with high performance properties. The aim of the research was to determine the effect of modifying additives on the properties of the matrix for the production of composites with high technical requirements. When performing research, we considered modifiers that interact differently with the components of the polymer matrix as plasticizers. The first type of additive is able to combine with reactive groups of epoxy resin to form a three-dimensional product. Urea resin was used as such a compound. The second group of samples contained a furfurolacetone monomer-a substance that does not contain reactive groups with the resin, but interacts with the hardener of the epoxy resin. And the third type of modifier is dioctyl phthalate, whose role is to change the intermolecular and intramolecular interaction of the spatial structure that it fills. Optimization of compositions to identify areas with high physical and mechanical values was carried out using mathematical methods of experiment planning. Based on the results of the research, it can be concluded that with the optimal content of plasticizers, in all cases, there is an increase in the compressive and tensile strength indicators compared to materials without additives. Further increase in the content of modifying additives (above the optimal amount) leads to a decrease in strength.

The need to create councils on the priority directions of scientific and technological development as part of the implementation of the Strategy for the Scientific and Technological Development of the Russian Federation following the example of the implementation of the Soviet national level nuclear project in which the cooperation of hundreds of scientific and production structures was important is demonstrated. Successful implementation of the tasks set then is closely associated with the All-Russia Institute of Aviation Materials and its scientists who made an invaluable contribution to the development of new materials. The key role of the institute today as an organization responsible for the implementation of the priority technological direction Materials Science Technologies and as a developer of new generation materials is presented.

Strontium aluminosilicate glass-ceramics modified with zirconia additions in the presence of yttria as a stabilizing oxide and without it have been prepared by a sol–gel process. Increasing the zirconia content from 5 to 15 wt % has been shown to reduce the gelation time of the starting solutions, lower the gel crystallization onset temperature, activate the glass-ceramic sintering process, and increase the critical stress intensity factor (KIc) of the glass-ceramics by more than a factor of 2. The present results confirm that the increase in KIc on the addition of ZrO2 is due to transformation toughening. At the same time, the addition of yttria as a stabilizing oxide has been shown to hinder the martensitic transformation of tetragonal ZrO2 into the monoclinic phase.