The article discusses the possibilities of preparing high-quality powder materials from heat-resistant light alloys based on refractory monoaluminides of nickel β-NiAl and ruthenium β-RuAl for the manufacture of compact samples/products of complex shape using additive technologies with minimal final machining. Additive technologies are based on the use of spherical precursor micro-powders with a regulated granulometric composition, good fluidity and an oxide-free surface. The possibilities of obtaining precursors from RuAl-based alloys by plasma spheroidization of powders obtained by crushing mixtures from scrap samples of alloys based on RuAl with various additives are considered.

A method for obtaining nanopowder microgranules of the W – Ni – Fe system (composition of the VNJ-90) of a micron size range by spray drying of a suspension based on composite nanoparticles obtained by plasma chemical synthesis is considered. The parameters of operation of the Buchi Mini Spray Dryer B-290 spray drying laboratory unit with an ultrasonic nozzle have been experimentally determined, providing for the production of nanopowder microgranules of VNJ-90 with an output of the target fraction of 25 – 63 µm at the level of 65 %. The dependence of the size and morphology of the obtained granules on the choice of the dispersion medium, the concentration of the dispersed phase and the organic binder in the suspension is established. The effect of the suspension flow rate during spray drying on the yield of granules of a fraction of 25 – 63 µm was evaluated. The test of the manufactured experimental sample of nanopowder microgranules in the process of plasma spheroidization was carried out.

A method for producing tungsten powder consisting of spherical microparticles with dimensions of 20 – 50 µm is considered when processing a granular tungsten nanopowder in a flow of argon electric arc thermal plasma. Experimental studies of plasma chemical synthesis of tungsten nanopowder in a plasma reactor with a limited jet flow during the interaction of tungsten trioxide with a flow of hydrogen-containing plasma generated in an electric arc plasma torch have been carried out. The conditions of spray drying and the properties of a suspension consisting of tungsten nanoparticles have been experimentally determined, ensuring the production of mechanically strong nanopowder microgranules of rounded shape with a homogeneous internal nanostructure that does not contain cavities, with the yield of microgranules with a size of less than 60 µm at the level of 65 %. The influence of the parameters of the plasma processing of nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the resulting particles has been established.

The possibility to obtain composite micropowders of the W−Cu system with spherical particles having sub-microscale/nanoscale internal structure was confirmed and studied using the complex multistage approach. Composite W−Cu nanoparticles with core–shell structure (W cores and Cu shells) were produced in plasmochemical synthesis in the first stage. Further spray-drying of the aqueous suspension of the W−Cu nanopowder with sucrose enabled the formation of 25−63 μm microgranules with a yield of 50%. The last step was the treatment of the nanopowder microgranules by a thermal plasma jet, which ensured the production of dense spherical W−Cu particles. The final powder had a spheroidization degree of 90%−95%, a bulk density of up to 8.1 g/cm3 and a flowability of 12 s/50 g. The contents of impurities in the resulting spherical micropowder were 0.7 wt.% O, 0.02−0.2 wt.% C and 0.03−0.05 wt.% H.

The process of obtaining powders from the 5–50 μm fraction of a W-Ni-Fe system consisting of particles with predominantly spherical shapes was investigated. Experimental studies on the plasma–chemical synthesis of a nanopowder composed of WNiFe-90 were carried out in a plasma reactor with a confined jet flow. A mixture of tungsten trioxide, nickel oxide, and iron oxide powders interacted with a flow of hydrogen-containing plasma generated in an electric-arc plasma torch. The parameters of the spray-drying process and the composition of a suspension consisting of WNiFe-90 nanoparticles were determined, which provided mechanically strong nanopowder microgranules with a rounded shape and a homogeneous internal structure that contained no cavities. The yield of the granule fraction under 50 μm was 60%. The influence of the process parameters of the plasma treatment of the nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the obtained particles, seen as their bulk density and fluidity, was established. It was shown that the plasma spheroidization of the microgranules of the W-Ni-Fe system promoted the formation of a submicron internal structure in the obtained spherical particles, which were characterized by an average tungsten grain size of 0.7 μm.

Additive manufacturing is a promising and actively developing method for the synthesis of metal products. The development of techniques for the production of spherical powder particles with specified properties from metals and alloys represents a significant challenge in the field of additive manufacturing. A new method for the production of titanium powders with spherical particles has been proposed, including the method of hydrogenation and dehydrogenation with subsequent spheroidization in thermal plasma. Titanium sponge, used as a feedstock, was saturated with hydrogen using the energy-efficient self-propagating high-temperature synthesis (SHS) method. The resulting hydride was then mechanically ground and then dehydrogenated by thermal decomposition in a vacuum furnace. The resulting precursor was subjected to plasma treatment, which resulted in a product (titanium powder) with a high degree of spheroidization. The physical, chemical, and technological parameters of the titanium powders were investigated. It was found that the final product, spherical titanium powder, has the necessary properties for use in additive manufacturing technologies.

The CompoNiAl-M5-3 high-temperature alloy based on nickel monoaluminide was obtained by selective laser melting (SLM) of a spheroidized powder with particle size in the range of 20 – 45 μm. The powder was manufactured using an integral technology including self-propagating high-temperature synthesis (SHS), briquette grinding, sieve and air classification followed with spheroidization of powder particles in a thermal plasma flow and ultrasonic purification of spheroidized particles from nanofraction. Using parametric studies, the SLM modes were tested on SLM 280H and TruPrint 1000 machines. Mechanical tests of the samples were carried out using the uniaxial compression scheme with the strain rate d ε/ dt = 10 –4 s –1 in the temperature range 1023 – 1273 K. Scanning and transmission electron microscopy methods were used to study the influence of laser spot size on the evolution of microstructure and thermomechanical properties of the SLM-consolidated material in comparison with that obtained by hot isostatic pressing (HIP). The authors established the effect of HIP + HT (aging in vacuum) post-treatment on the structure and mechanical properties of the material. The yield strength at 1073 K of the alloy built on the additive machine with a laser spot diameter of 38 μm after SLM + HIP + HT was 500 MPa, which exceeded the yield strength of the HIP-samples by 220 MPa.

The article proposes a method for producing Ti and Zr-based alloys in the form of powders with a high degree of particle sphericity. According to this method, a Zr35Ti30Be27,5Сu7,5 alloy amorphous powder with a particle sphericity of more than 99% and fractional composition of 63-100 μm was obtained. Bulk samples were made by the method of spark plasma sintering (SPS) with varying parameters: temperature, pressure and dwelling time. It was determined that the samples have an X-ray amorphous structure during SPS in the temperature range of 320–340 °C. It was found that the best compaction is achieved at a temperature of 340 °C. However, the samples have boundaries at the points of contact of the particles with each other, which negatively affects microhardness. The analysis carried out by the EELS shows that oxides form on the surface of the particles, which interfere with SPS.

The report presents the results of R&D of plasma-chemical production of W nanopowders, W-Cu, W-C, W-Ni-Fe powder nanocomposites, WC tungsten monocarbide, as well as spherical micropowders of these compounds for their use in modern 3D printing technologies. Plasma-chemical synthesis of tungsten nanopowder is based on the reduction of tungsten oxide compounds powders in a stream of hydrogen-containing low-temperature thermal plasma generated in an electric arc plasma torch. The synthesis of W-Cu and W-Ni-Fe nanocomposites is carried out using the reduction of a mixture of the metal oxides, Using the synthesized tungsten-based nanocomposites powders, spherical composite micropowders with a submicron structure can be manufactured by granulation of nanopowders and subsequent spheroidization of granules by melting in a low-temperature thermal plasma. The results of the development of DC arc plasma systems for the synthesis of nanopowders and micropowders spheroidization are presented.

The powder of 93 W – 4.9 Ni – 2.1 Fe (VNZh-93) pseudo-alloy with a spherical particle shape in the size range of 15 – 50 μm with a grain size of 0.5 – 3 μm was obtained using plasma chemical synthesis, granulation and spheroidization technologies. The possibility of using spheroidized powder VNZh-93 in additive 3D-printing is demonstrated. Studies of the physical and mechanical characteristics and microstructure of VNZh-93 test samples made using the selective laser melting technology (SLM) have been carried out. It is shown that the parameters of the SLM significantly affect the formation of the microstructure of test samples. It is possible to form a homogeneous equiaxed microstructure with an average grain size of about 1 micron using optimal SLM modes. It is shown that maximum density and Vickers hardness of VNZh-93 obtained in optimal SLM modes are 16.8 g/cm3 and 480 HV, respectively. These values are not inferior to the values for VNZh-93 samples obtained using traditional liquid-phase sintering technology. At the same time, the main problem of selective laser melting of VNZh-93 powder is the heterogeneity of the bulk samples microstructure and the formation of microcracks and micropores in their structure.

For the first time, a powder of W-5Ni-2Fe composition with spherical particles from 15 to 50 microns and a tungsten grain size from 0.5 to 3 microns was obtained using a new technological approach, developed by the authors, based on plasma spheroidization of powder granules made from nanoparticles synthesized in a plasma chemical process. The possibility of using the obtained spheroidized powder W-5Ni-2Fe in the process of selective laser melting (SLM) has been proved. The microstructure, physical, and mechanical characteristics of experimental samples made using SLM technology from the produced W-5Ni-2Fe powder have been studied. The results of the performed studies have shown that the microstructure of experimental samples is extremely dependent on the parameters of the SLM process. The precise choice of the SLM process mode made it possible to obtain a homogeneous structure of experimental samples of tungsten heavy alloy (WHA), with a tungsten grain size of about 1–2 microns, which is much smaller than the tungsten grain size in traditional heavy alloys. This creates prerequisites for increasing the strength characteristics of parts of complex shapes made by the SLM method from such powders. The maximum values of density and hardness of experimental samples obtained in the conducted studies are not worse than the values of samples obtained using traditional liquid-phase sintering technology. It is determined that the main problem of SLM powder W-5Ni-2Fe during investigation is the heterogeneity of the microstructure of massive samples and the formation of micropores and microcracks.

The NiAl–Cr–Co–X alloys were produced by centrifugal self-propagating high-temperature synthesis (SHS) casting. The effects of dopants X = La, Mo, Zr, Ta, and Re on combustion, as well as the phase composition, structure, and properties of the resulting cast alloys, have been studied. The greatest improvement in overall properties was achieved when the alloys were co-doped with 15% Mo and 1.5% Re. By forming a ductile matrix, molybdenum enhanced strength characteristics up to the values σucs = 1604 ± 80 MPa, σys = 1520 ± 80 MPa, and εpd = 0.79%, while annealing at T = 1250 ℃ and t = 180 min improved strength characteristics to the following level: σucs = 1800 ± 80 MPa, σys = 1670 ± 80 MPa, and εpd = 1.58%. Rhenium modified the structure of the alloy and further improved its properties. The mechanical properties of the NiAl, ZrNi5, Ni0.92Ta0.08, (Al,Ta)Ni3, and Al(Re,Ni)3 phases were determined by nanoindentation. The three-level hierarchical structure of the NiAl–Cr–Co+15%Mo alloy was identified. The optimal plasma treatment regime was identified, and narrow-fraction powders (fraction 8–27 µm) characterized by 95% degree of spheroidization and the content of nanosized fraction <5% were obtained.

The influence of the addition of 2.3 at.-% Y and of 0.8 at.-% Zr + 0.2 at.-% Y on the properties of TiAl43Nb4Mo1B0.1 (TNM-B1) titanium aluminide alloy is investigated. Energy-dispersive X-ray spectroscopy analysis shows that the Y content of the β, γ, and α2 phases is low, and nearly all of the Y is in the Al2Y phase. The Zr content in the alloy phases is the same as that in alloy. Tensile tests show that Y addition decreases tensile strength and elongation, but only minor effects on these properties are observed after the addition of Zr and Y. It is shown that the addition of Y leads to a decrease in the heat resistance of TiAl43Nb4Mo1B0.1 alloy at 900°C.

Spheroidization of Fe and steel powders in a plasma stream of an DC arc plasma torch is investigated. The possibility of obtaining a product with a spherical particle content of up to 100% is established. The fluidity of the best samples of obtained powder is 13–20 s with a fluidity of the feedstock of 39 s. The bulk density of the initial powder (3.05 g/cm 3 ) during the plasma treatment increases to 4.1–4.4 g/cm 3 . The nanofraction content in spheroidized powders varied from 0 to 75 wt % and it depends mainly on the enthalpy of the plasma stream, consumption of raw materials, and the organization of the flow of the plasma-forming gas in the discharge channel of the plasma torch. It is established that Fe powders spheroidized in plasma can be used in selective laser melting technology to obtain compact samples whose density reaches 7.86 g/cm 3 .

The results of work on the implementation of plasma synthesis and spheroidization of powders of metals and their compounds in a thermal plasma generated in a direct current arc plasma torch are presented. The possibility of controlling the properties of the obtained powders is demonstrated.

Spheroidization of micropowders of a heat-resistant alloy based on nickel aluminide with a particle size of 20 to 45 μm was studied. The alloy was produced by calcium hydride reduction (CHR) and elemental synthesis (SHS). The spheroidization was carried out in a flow of argon–hydrogen thermal plasma generated by a direct-current (DC) plasma torch. The degree of spheroidization of the micropowders reached 98.5%, and the flowability was 20 s/50 g.

Spherical Nb-Si powder alloy is a perspective material to manufacture products for the aerospace industry by additive technologies. Nb-16Si (at.%) powder alloy was prepared by mechanical alloying from pure elemental powders using planetary ball mill Fritsch Pulverisette 4. Spheroidization was carried out on plasma generator based on thermal plasma arc generator with vortex discharge stabilization. Experimental results show that plasma spheroidizing of Nb-16Si powders obtained by mechanical alloying is possible. It is shown that after the spheroidization the particle surface is rough which indicates the cast structure of the material. Three phases having different optical contrast are revealed on microsections: Nb5Si3, Nb3Si and Nbss, which is confirmed by X-ray diffraction. It is shown that the main peaks in the X-ray graph after MA correspond to a solid solution of niobium with a cubic lattice and the parameter a = 0.333 nm, as well as niobium silicide Nb5Si3 with a hexagonal lattice (P63/m) a = 0.7536 nm and c = 0.5249 nm. After spheroidization the hexagonal lattice of niobium silicide Nb5Si3 is transformed into a tetragonal lattice (I4/m) with the parameter a = 0.6557 nm and c = 1.186 nm. The other phase components remain unchanged.

The development of new, more refractory heat-resistant materials for gas-turbine engines is one of most important problems of modern materials science. This is associated with the fact that nickel superalloys currently used for this purpose have a lower melting point of ~1400°C, which limits their own maximal working temperature by a range of 1100–1150°C. The Ni alloys can be replaced by natural composites, in which refractory metals are a matrix, while their silicides are intermetallic hardeners. Only three “refractory metal–silicon” binary systems manifest stability to the Me5Si3 silicide, notably, Nb5Si3, Re5Si3, and W5Si3. From the viewpoint of a combination of a high melting point and a low density, the Nb5Si3 compound is optimal among other silicides. The use of alloys of the Nb–Si system in additive manufacturing machines is of considerable interest. This work presents the results of experimental investigations into the treatment of the Nb–16 at % Si powder fabricated using mechanical alloying of elemental Nb and Si powders in the thermal plasma flux. The Nb–16Si alloy powder is fabricated by the mechanical alloying of powders of pure elements in a Fritsch Pulverisette 4 planetary mill. The powder spheroidization is performed in a plasma installation based on a discharge vortex-stabilized electric-arc thermal plasma generator. Based on the results of experimental investigations, the principal possibility to perform the plasma spheroidization of particles of the Nb–16Si alloy prepared by mechanical alloying is shown. It is shown that the surface of spheroidized particles is rough and reflects the cast material structure. Three phase components Nb5Si3, Nb3Si, and Nbss having different optical contrast are revealed in microslices, which is confirmed by X-ray phase analysis.