The paper presents the results of research carried out at the O.V. Roman Powder Metallurgy Institute (Belarus) on the production of iron-based pseu-dosalloys for antifriction applications and the development of methods for im-proving their mechanical and tribological properties. A computational model of parametrically non-stationary high-temperature infiltration was developed, enab­ling the calculation of pore-filling time and optimization of the pseudosalloy fabrication mode. The features of carbon distribution in the iron skeleton of the pseudosalloy during isothermal holding and subsequent heat treatment under the influence of the copper phase were identified. It was shown that after isothermal holding, the carbon content in the region of the skeleton adjacent to the copper phase is lower than in its center, whereas after quenching and high-temperature tempering, a carbon-enriched zone forms at the interface with the copper phase. The mechanisms responsible for improving the mechanical and tribological prop-erties of pseudosalloys using the developed methods were established. These in-clude: stamping at the optimum temperature; extended holding during high-tempe­rature tempering after quenching; high- and low-temperature thermome-chanical treatments under optimized conditions; alloying the iron matrix with nickel or chromium; and structural modification through the introduction of ul-tradispersed diamonds, ultradispersed aluminum oxide, nanodispersed zirconium oxide, mixtures of nanosized oxides of iron, nickel, and zinc, single- or two-phase aluminides of nickel, iron, or titanium and their composites, calcium molybdate, or hexagonal boron nitride, as well as alloying the infiltrate with tin, nickel, or chromium and the addition of ultradispersed aluminum oxide. The obtained strength, hardness, impact toughness, friction coefficient, limit seizure pressure, wear resistance, and PV parameter values are reported. The wear mechanism of pseudosalloys with enhanced properties was determined. It was demonstrated that during friction, nanoscale porosity and voids form, serving as additional res-ervoirs for lubricant, thereby improving friction conditions, preventing copper transfer into these areas, reducing the coefficient of friction, and increasing wear resistance.

Research in the field of titanium powder metallurgy has been ongoing for more than 60 years. Nevertheless, there are relatively few examples of the practical application of powder titanium, which is associated with insufficient reliability and durability of the manufactured products. The ability of titanium parts to withstand static and dynamic loads is determined by residual porosity, non-metallic inclusions, and microstructural characteristics. At present, the most widely used method for producing powder titanium components is the press–sinter route. However, the porosity of sintered titanium typically ranges from 3 to 15 %, which reduces its load-bearing capacity and highlights the need for effective methods to minimize porosity. Hot working methods, particularly hot die forging of porous preforms, hold considerable potential in addressing this issue. This study presents the results of investigating the features of densification, structure formation, and properties of powder titanium under hot die forging. A technology for producing hot-forged powder titanium is proposed, which includes hydriding–dehydriding of porous preforms. This operation promotes the reduction of oxides localized on the surfaces of open pores by hydrogen and their activation, thereby improving conditions for interparticle bonding during subsequent hot repressing. As a result, the obtained samples demonstrate higher fracture toughness and ductility compared with reference samples. The values of the maximum specific work of hot densification of porous powder titanium, required to achieve monolithic density at different preheating temperatures of the preforms, were determined. It was shown that the non-monotonic temperature dependence of the maximum specific densification work is associated with the formation of a coarse-grained structure and with reduced ductility of the deformable material in the temperature range of the α → β phase transformation.

Tantalum–zirconium carbide Ta₄ZrC₅ was synthesized by the method of self-propagating high-temperature synthesis (SHS) in the thermal explosion mode. The mechanism of its formation was investigated, including processes occurring during the heating of precursor mixtures to the ignition temperature, which proceed in the solid phase. The interaction of molten bimetallic Ta₄Zr particles with carbon was also studied. The initial powder mixtures were prepared in two stages. In the first stage, high-energy ball milling (HEBM) in an AGO-2 mill under an argon atmosphere was employed to carry out mechanical alloying (MA) of tantalum with zirconium, resulting in the formation of bimetallic Ta₄Zr particles representing a solid solution of zirconium in tantalum. Upon heating, ordering of the solid solution occurred, accompanied by a small exothermic effect depending on the MA duration. In the second stage, the obtained Ta₄Zr powder was mixed with carbon black and heated to the thermal explosion temperature (900–1250 °C), leading to the formation of Ta₄ZrC₅. For the first time, to study the mechanism of high-temperature interaction of Ta₄Zr bimetallic particles with carbon, the particles were deposited onto a graphite substrate and heated in vacuum at a residual pressure of 10^–3 Pa, with the substrate temperature reaching up to 3000 °C. Depending on particle size, two modes of interaction of molten Ta₄Zr particles with the graphite substrate were observed. Particles smaller than 10 μm, due to surface tension forces, did not spread on the substrate upon melting; instead, they absorbed carbon and sank into it. Larger particles spread over the substrate, with the melt being depleted in zirconium, which more actively interacted with carbon.

Corrosion of thermal barrier coatings on gas turbine engine components made of heat-resistant alloys, caused by interaction with molten silicate deposits (CMAS), reduces their high-temperature stability and leads to premature failure during service. The problem of CMAS resistance in coatings with an outer ceramic layer of yttria-stabilized zirconia (YSZ) remains highly relevant, and its solution has important practical implications. The present study focused on zirconia-based ceramic materials used for the deposition of thermal barrier coatings. The interaction of ceramic coatings with silicate deposits was investigated at temperatures up to 1300 °C. Scanning elect­ron microscopy, energy-dispersive spectroscopy, thermogravimetric/differential thermal analysis, and X-ray diffraction were employed to study the interaction of CMAS with YSZ on model samples prepared from powders of grades Z7Y10-80A, Zr7Y20-60, and Metco 204NS with different morphologies. The interaction mechanism between CMAS and YSZ at 1200–1300 °C was established. It was shown that the nature and intensity of the interaction strongly depend on the structure and morphology of the ceramic particles. The dense particle structure of ceramics based on Z7Y10-80A and Metco 204NS powders reduces CMAS penetration, in contrast to Zr7Y20-60 powders with a more porous particle structure. The interaction mechanism between CMAS and YSZ was found to be the same for all ceramics studied and occurs through dissolution–precipitation of zirconia in the glass melt. It was demonstrated that with increasing temperature, the degree of zirconia tetragonality changes due to the reduction of yttrium content caused by its diffusion into the glass. This can lead to a polymorphic transformation of zirconia accompanied by volume expansion, followed by cracking and spallation of the thermal barrier coating.

The regularities of formation of wear- and oxidation-resistant coating under combined electrospark and cathodic-arc treatment (ESCAT) of AZhK superalloy were studied. The effect of electrode polarity and rare-earth (Ce, Er) microalloying of Al–Ca-based rod electrodes on the structure, strengthening and oxidation resistance of the deposited coatings was studied. It was found that anodic polarity secures the formation of crack-free coatings predominantly composed of γ′-Ni₃Al intermetallic (L1₂-type structure, 3.600 Å). These coa­tings reached a thickness of 15–20 μm due to the oriented growth of crystallites with a transverse size below 300 nm. In contrast, the coa­tings formed at cathodic polarity have consisted of two intermetallic phases: β-NiAl (B2 structure, 2.895 Å) and γ′-Ni₃Al (L1₂, 3.595 Å). Structural and phase transformations occurring during the treatment of a AZhK substrate (initial hardness of 5.2 GPa) using electrodes of different polarities constitute the dominant strengthening factors. The maximum hardness (12.3 GPa) was recorded for coatings composed of β-NiAl and γ′-Ni₃Al phases. Coatings obtained with anodic electrode polarity exhibited relatively lower hardness values (7.3 GPa) accompanied by low elastic modulus values (112 GPa). The wear rate of these coatings ranged from 6 to 7.5·10^–5 mm³/(N·m), representing a sixfold improvement of wear resistance compared to the untreated AZhK alloy. In-situ TEM studies revealed excellent thermal stability of the γ′-Ni₃Al intermetallic structure upon heating the coating lamellae cut of the coating obtained under anodic polarity up to 700 °C. Results of high-temperature oxidation tests at 1000 °C indicate that the coating the AZhK alloy change the oxidation law from linear to logarithmic one. The minimum thickness of the oxide layer (about 3 μm) was found in the coatings obtained by ESCAT using Al–Ca–Er electrode with anodic polarity. That is 10 times less than the thickness of the oxide layer of AZhK alloy. The change of oxidation law during annealing to the logarithmic one is due to in-situ formed the NiAl₂O₄/α-Al₂O₃ barrier layer strengthened with CaMoO₄ particles. It slowing down of oxygen diffusion in bulk of substrate providing its excellent oxidation resistance.

This paper presents a review of recent advances in functionally graded additive manufacturing using selective laser melting (SLM, also referred to as laser powder bed fusion, LPBF). The fundamental principles of producing functionally graded pro­ducts by SLM are discussed, including approaches to forming compositional and structural gradients. Particular attention is given to the formation of the transition layer in the synthesized material, which is crucial for achieving the desired properties of the pro­ducts. Methods of design and numerical modeling of functionally graded structures are analyzed, including the use of artificial intelligence and machine learning. It is demonstrated that applying bio-inspired design principles enables the development of parts with enhanced mechanical, thermal, and functional properties. Examples are provided of successful fabrication of multi-material products with tailored property anisotropy, as well as products with controlled porosity gradients. The promising application areas of functionally graded products are identified, including aerospace, medicine, mechanical engineering, and energy.

This paper reviews the main methods for producing and assessing the quality of powder feedstock intended for use in laser powder bed fusion (LPBF). The LPBF process involves the layer-by-layer laser fusion of powder feedstock on the surface of a build plate in accordance with a 3D model. The study examined powder feedstock produced domestically from industrial alloys based on nickel (Inconel 718, EP741NP, AZhK), titanium (VT6, VT6s, VT20), and iron (12Kh18N10T, Fe–Cr–Ni–Co–Mo system). The principal production methods considered are gas atomization, the Plasma Rotating Electrode Process (PREP), and plasma atomization in an inert gas atmosphere, with their respective advantages and limitations described. The most common defects in powder feedstock arising during production and use in LPBF are analyzed, including non-conforming particle size distribution, internal porosity, satellites, changes in bulk density and flowability, fine black particles, increased gaseous impurities, and non-conforming chemical composition. Measures for mitigating these defects and maintaining product quality are proposed. The findings show that achieving stable LPBF results requires regular quality control of powder feedstock to ensure compliance with the requirements specified in applicable standards, including particle size distribution (distribution quantiles d₁₀, d₅₀, and d₉₀), processing characteristics, particle morphology, chemical composition, and moisture content. For certain alloys, when defects occur systematically and cannot be effectively eliminated through process adjustments or post-processing, the most appropriate solution is to change the powder production method.