Powder Metallurgy and Metal Ceramics最新文献

{"title":"Preparation of Boehmite by the Hydrothermal Method and Analysis of its Dehydration Kinetics","authors":"Yanhua Sun,&nbsp;Zhongxiang Shi,&nbsp;Jing Wang,&nbsp;Kenan Xu","doi":"10.1007/s11106-025-00497-x","DOIUrl":"10.1007/s11106-025-00497-x","url":null,"abstract":"<p>Boehmite (AlOOH), due to its porous structure, excellent adsorption properties and high thermal stability, is widely used in various areas, including petrochemistry, biology and medicine (catalysts, flame retardants, functional ceramics, etc.). We propose replacing traditional Al salts (or Al alkoxides) with industrial-grade aluminium hydroxide Al(OH)₃ as the precursor and using a hydrothermal method to synthesise phase-pure boehmite powder. The phase transition from gibbsite to boehmite can be achieved by adjusting the hydrothermal temperature using industrial-grade aluminum hydroxide (Al(OH)₃) as the starting material. Based on this, the study investigated the influence of hydrothermal reaction temperature on the crystal structure and microscopic morphology of boehmite. The samples were characterized using a variety of analytical methods, including XRD, SEM, TEM, HRTEM, particle size distribution, and TG–DSC, to comprehensively analyze the phase, microscopic morphology, and phase transition process. Results demonstrate that pure-phase boehmite powder with a square plate-like morphology can be obtained at hydrothermal temperatures above 180°C. The square plates exhibit smooth surfaces, clear boundaries, and an average particle size of approximately 0.88 μm. Dehydration kinetics analysis using the Popescu method confirms that the synthesized boehmite has a thermal decomposition temperature above 700K and a dehydration weight loss of 17%. The dehydration process follows a model mechanism function of f(α) = 2(1 – α)^1/2, indicating a two-dimensional phase boundary reaction of shrinking cylindrical bodies. The average activation energy (E_a) for the dehydration process is determined to be 211.40 kJ/mol, the average pre-exponential factor (A) is 5.05 · 10¹³ min^–1, and the average correlation coefficient (R²) is 0.9939.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"712 - 721"},"PeriodicalIF":0.6,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advanced Approaches For Producing Nanocrystalline and Fine-Grained ZrO2-Based Powders (Review) IV. Biological Methods (Green Synthesis)","authors":"O. V. Dudnik,&nbsp;S. M. Lakiza,&nbsp;I. O. Marek,&nbsp;V. P. Red’ko,&nbsp;A. O. Makudera,&nbsp;O. K. Ruban","doi":"10.1007/s11106-025-00495-z","DOIUrl":"10.1007/s11106-025-00495-z","url":null,"abstract":"<p>Biological methods (green synthesis) involving natural sources (bacteria, fungi, algae, plants, etc.) were developed in the 21st century in South and East Asia, South America, and Middle East countries. The mechanism of ZrO₂ nanoparticle formation using microbial systems (bacteria and fungi) includes biosorption and bioreduction. Rounded and rod-shaped primary particles, comprising a mixture of m-ZrO₂ and t-ZrO₂ phases, were synthesized. These powders exhibit effective antimicrobial and antibiofilm activity and are promising for the delivery of pH-sensitive drugs and the development of biosensors. The use of various plant extracts in thermal decomposition, coprecipitation, sol–gel processes, solution combustion, and hydrothermal synthesis was explored. The growth of ZrO₂ nanoparticles during green synthesis proceeds through three stages: activation, growth, and termination. The resulting ZrO₂ powders hold promise for applications in novel antimicrobial agents, anticancer drugs, photocatalysts for wastewater treatment, fillers in polymer nanocomposites, and nanoadditives to enhance the efficiency of diesel engines. Composite powders such as ZrO₂/RGO with improved anticancer properties, ZrO₂/PdO and ZrO₂ : Sm³⁺ (11 mol.%) for photocatalysts, and ZrO₂ : Mg (0.1–5 mol.%) for nanophosphors in display devices were developed. The choice of the synthesis route for the starting powders is based on the intended application of the final material. The synergistic effect of physicochemical and biological approaches in green synthesis expands the potential for microstructural design of functional ZrO₂-based materials for diverse applications.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"687 - 701"},"PeriodicalIF":0.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Refining the Understanding of the Thermionic Emission Mechanism in Impregnated WBa and ScBa Cathodes Based on G.V. Samsonov’s Configurational Model I. Analysis of the Chemical Composition and Structure of the Emission–Adsorption Layer in WBa and ScBa Cathodes","authors":"I. O. Podchernyaeva,&nbsp;O. I. Hetman","doi":"10.1007/s11106-025-00498-w","DOIUrl":"10.1007/s11106-025-00498-w","url":null,"abstract":"&lt;p&gt;The first part presents an analysis of existing experimental studies on various types of impregnated WBa and ScBa cathodes (WBa-ICs and ScBa-ICs), underlying the development of polarization and semiconductor thermionic emission models intended to clarify the mechanisms whereby CaO and Sc&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; oxides and platinum-group metals influence cathode emission. The analysis of existing polarization and semiconductor WBa-IC and ScBa-IC thermionic emission models shows that there is no universally accepted thermionic emission model. An interpretation of the chemical composition and structure of the emission–adsorption layer (EAL) in WBa-ICs is proposed. This interpretation serves as the basis for evaluating interatomic interactions within the EAL, relying on G.V. Samsonov’s configurational model of the electronic structure in solids. The EAL on the tungsten adsorbent in WBa-ICs consists of two structural–phase components: a two-dimensional Ba–O monolayer adsorbed on the tungsten surface and three-dimensional BaO–CaO oxides located within the pores and along their perimeters in the tungsten skeleton. The chemical composition and structure of the EAL in ScBa-ICs depend on the production technology. There is currently no consensus regarding the role of scandium and scandium-containing compounds in the characteristics of ScBa-ICs, which prevents the development of a unified thermionic emission model for ScBa-ICs. The polarization WBa-IC and ScBa-IC thermionic emission model proposed in the second part is for the first time analyzed from the standpoint of G.V. Samsonov’s configurational model. The new polarization model differs from existing ones in that it incorporates donor–acceptor interactions among valence orbitals of the adatoms within the EAL and between these adatoms and atoms of the adsorbent, initiated by changes in the energy stability of valence orbital configurations. In the proposed polarization WBa-IC and ScBa-IC thermionic emission model, the electron work function is determined by the potential barriers of polarized dipole complexes of two types. The first type is formed through donor–acceptor interactions between adatoms themselves and between adatoms and adsorbent atoms Ba (Ca, Sc)&lt;sup&gt;+&lt;/sup&gt;–O&lt;sup&gt;–&lt;/sup&gt;–A&lt;sup&gt;+&lt;/sup&gt;. The second type involves adsorbed oxide molecules interacting with adsorbent atoms Ba&lt;sup&gt;+&lt;/sup&gt;O&lt;sup&gt;–&lt;/sup&gt; (Ca&lt;sup&gt;+&lt;/sup&gt;O&lt;sup&gt;–&lt;/sup&gt;)–A&lt;sup&gt;+&lt;/sup&gt;, (&lt;span&gt;({text{Ba}}^{+}{text{O}}^{-}-{text{Sc}}_{2}^{+}{text{O}}_{3}^{-}-{text{Al}}_{2}^{+}{text{O}}_{3}^{-})&lt;/span&gt;)–A&lt;sup&gt;+&lt;/sup&gt;, and (&lt;span&gt;({text{Ba}}^{+}{text{O}}^{-}-{text{Sc}}_{2}^{+}{text{O}}_{3}^{-}-{text{W}}^{+}{text{O}}_{3}^{-})&lt;/span&gt;)–A&lt;sup&gt;+&lt;/sup&gt;. In all these complexes, the bond between the adsorbate and the adsorbent is mediated by oxygen, acting as an electron acceptor. The characteristics of the donor–acceptor interaction are defined by the energy stability of valence orbital configurations, d&lt;sup&gt;0&lt;/sup&gt;, d&lt;sup&gt;5&lt;/sup&gt;, and d&lt;sup&gt;","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"722 - 734"},"PeriodicalIF":0.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of the Size and Mechanical Strength of Natural Diamond Grains in the Matrix of Diamond Tube Drills on Their Performances in the Drilling of Selected Nonmetallic Materials","authors":"V. P. Umansky,&nbsp;V. P. Krasovskyy,&nbsp;O. O. Bashchenko","doi":"10.1007/s11106-025-00499-9","DOIUrl":"10.1007/s11106-025-00499-9","url":null,"abstract":"<p>Six diamond tube drills were fabricated by vacuum impregnation using cutting grains of natural diamonds of grade A1 with grain sizes of 250/200, 315/250, 500/400, 800/600, 1000/800, and 1200/1000 μm. For comparative analysis, three drills were produced with synthetic diamonds of grades AS32 500/400, AS400 315/250, and AS400 500/400 (DSTU 3292–95). To ensure reliable fixation in the tool body, diamond grains coated with molybdenum and copper were embedded in a Cu–15 wt.% Sn matrix with added fillers (5 wt.% ultrafine diamond powder of grade ASM 1/0 and molybdenum). The compressive strength of the diamond grains was evaluated. The paper presents results from comparative laboratory tests of the diamond drills in marble, granite, and silicon carbide-based abrasive stone. Performance characteristics—drilling speed and drill wear—were studied as functions of the natural diamond grade used. The drilling speed depended on the size of the diamond grains. The lowest drilling speeds (3.52, 6.83, and 23.1 mm/min for granite, marble, and abrasive stone) were observed in drills equipped with small (A1 250/200 μm) and weak (50 N) diamond grains. When larger (A1 1200/1000 μm) and stronger (350 N) diamond grains were used, the drilling speed increased significantly (by approximately 4, 3.2, and 3.8 times) to 14.07, 22.1, and 87.99 mm/min for granite, marble, and abrasive stone, respectively. The lowest drilling speed observed in granite with all tested drills was due to its high hardness, being approximately twice that of marble. However, despite even greater hardness of silicon carbide, forming the base of the abrasive stone, the drilling speed remained high. When marble was drilled with tools containing the smallest diamond grains (A1 250/200 μm), their wear amounted to 0.0139 g. For harder materials (granite and abrasive stone), tool wear increased significantly (by factors of 41 and 48), reaching 0.5701 and 0.6665 g. With increasing grain size and compressive strength of the natural diamond grains, drill wear decreased, by factors of approximately 8, 317, and 14 for marble, granite, and abrasive stone. The greatest reduction in wear was recorded for granite. As a result, drills equipped with large and strong diamond grains (A1 1000/800 and A1 1200/1000) exhibited similarly minimal wear in the drilling of marble and granite: 0.0036 and 0.0018 g for granite and 0.0035 and 0.0017 g for marble.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"735 - 741"},"PeriodicalIF":0.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acoustic Study of Elasticity and Damping Properties of Polypropylene Composites Reinforced with Titanium Nitride Particles for 3D Printing","authors":"O. V. Vdovychenko,&nbsp;O. B. Zgalat-Lozynskyy,&nbsp;A. M. Kolesnykov,&nbsp;O. O. Matviichuk","doi":"10.1007/s11106-025-00496-y","DOIUrl":"10.1007/s11106-025-00496-y","url":null,"abstract":"<p>Composite materials reinforced with titanium nitride particles, which serve as the basis for manufacturing 3D-printed components that are promising for use in extreme environments, such as cutting tools, wear-resistant and protective coatings, biomedical products, and electrochemical energy capacitors, were studied. Linear and nonlinear acoustic methods were employed to evaluate the elastic and damping properties of polypropylene-based composites reinforced with up to 46 vol.% titanium nitride particles. When the volume content of titanium nitride particles raised from 20% to 46%, Young’s modulus of the composites was found to increase from 4.91 to 9.77 GPa and their shear modulus from 1.85 to 3.55 GPa. The dependence of both elastic moduli on the ceramic volume content over the studied range can be described with satisfactory accuracy by the Halpin–Tsai equation, using an empirical reinforcement particle shape factor of 4.2, which closely matches the experimentally determined value. The damping capacity of the studied composites ranged from 0.06 to 0.12 and was slightly lower in the composite with the higher titanium nitride content. The damping behavior of the composites as a function of the maximum cyclic strain amplitude exhibited a minimum at stress levels around 2.5 MPa. At the same stress levels, a discontinuity in the amplitude dependence of the relative resonance frequency shift was observed. The authors attribute both phenomena to structural transformations within the composite that occur during cyclic deformation under the specified amplitudes and oscillation frequencies. The results demonstrate the potential of acoustic nondestructive methods to monitor the quality of filaments for 3D printing and finished composite products.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"702 - 711"},"PeriodicalIF":0.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnesium-Based Foams: Fabrication Methods and Properties","authors":"Naveen Kumar,&nbsp;Sugandha Aachhera,&nbsp;Jyoti Kumari,&nbsp;Devendra Prasad,&nbsp;Ajaya Bharti,&nbsp;R. A. Kapgate","doi":"10.1007/s11106-025-00492-2","DOIUrl":"10.1007/s11106-025-00492-2","url":null,"abstract":"<p>Innovative applications such as lightweight structural and energy-absorbing uses have been found for magnesium-based foams due to their exceptional properties, such as low density, high specific strength, and excellent energy absorption. This review explores the influence of various space holder materials and manufacturing methods on the structural, mechanical, and thermal properties of magnesium-based foams. Key observations indicate that specific energy absorption is improved with certain space holders and manufacturing techniques, while corrosion resistance is significantly enhanced with higher space holder fractions. However, increasing porosity reduces thermal conductivity and peak compressive strength, highlighting the trade-offs in foam design. Comparisons among stir casting, powder metallurgy, and melt foaming methods reveal notable differences in density, mechanical strength, and corrosion resistance. Stir casting produces Mg foams with a density of 1.57 g/cc and a porosity of 16.5%, offering moderate mechanical strength (peak compressive stress ~208 MPa) and corrosion resistance. Powder metallurgy yields highly porous foams (up to 84.5%) with lower density (0.28 g/cc) but reduced strength (~30 MPa) and corrosion resistance. Melt foaming balances porosity (44.6%) and strength (56.97 MPa), making it suitable for energy absorption, though corrosion resistance varies with processing conditions. Furthermore, thermal conductivity studies suggest that magnesium foams can be tailored for applications requiring thermal insulation. The results underscore the need for optimized manufacturing techniques and tailored space holder materials to achieve the desired balance of properties. Optimization can be achieved by carefully controlling porosity levels, selecting suitable space holder materials, and fine-tuning processing parameters, such as sintering temperature and infiltration conditions, to balance mechanical strength and thermal insulation. This review provides a comprehensive understanding of the current advancements in magnesium foam research and outlines the pathways for developing next-generation magnesium foams for diverse industrial and biomedical applications.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"640 - 653"},"PeriodicalIF":0.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Information on the Annual Report of the Ukrainian Commission of Phase Diagrams and Thermodynamics (2024)","authors":"M. A. Turchanin,&nbsp;K. Ye. Korniyenko,&nbsp;T. Ya. Velikanova","doi":"10.1007/s11106-025-00500-5","DOIUrl":"10.1007/s11106-025-00500-5","url":null,"abstract":"<p>In 2024, the Ukrainian Commission on Phase Diagrams and Thermodynamics, an integral component of the Alloy Phase Diagram International Commission (APDIC), comprising 18 representatives from 26 countries, commemorated its thirtieth anniversary. The exchange of scientific information and coordination of activities of the international scientific community, mainly in the field of phase diagrams and thermodynamics, promoting the application of phase diagrams in industry and fundamental science, and dissemination of the methodology of critical evaluation of scientific information in world science are among the priority tasks of the APDIC's activity.— As part of the annual report of the Ukrainian Commission, at the APDIC meeting on May 31, 2024, information was presented on the results of Ukrainian scientists' activities in this field for 2023. It is presented in the form of a table with data on the studied systems and obtained results, and a list of references to published papers. Scientists from the Frantsevich Institute for Problems of Materials (National Academy of Sciences of Ukraine, Kyiv), Taras Shevchenko National University of Kyiv (Ministry of Education and Science of Ukraine, Kyiv), and Donbas State Engineering Academy (Ministry of Education and Science of Ukraine, Kramatorsk) provided relevant information to the Ukrainian Commission.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"742 - 747"},"PeriodicalIF":0.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Density, La and Si Content on the Mechanical and Electrical Properties, High-Temperature Oxidation of Sintering Ferritic Stainless Steel","authors":"Shuangfei Yan,&nbsp;Yi Cai,&nbsp;Chen Ou,&nbsp;Jiao Tian,&nbsp;Ziqi Liu,&nbsp;Rongsheng Wang,&nbsp;Jingguang Peng","doi":"10.1007/s11106-025-00494-0","DOIUrl":"10.1007/s11106-025-00494-0","url":null,"abstract":"<p>Solid oxide fuel cells (SOFCs) are considered a high-efficiency technology for energy conversion. Ferritic stainless steel has become the preferred material for interconnects due to its proper coefficient of thermal expansion, ease of processing, and economy. This study aims to investigate the effects of density, La, and Si content on the mechanical, high-temperature oxidation, and electrical properties of powder metallurgy ferritic stainless steel used for SOFCs interconnects. Ferritic stainless steel water atomized powders with varying contents of La and Si were pressed at 600 and 700 MPa, and then sintered at 1380°C for 3 h in a hydrogen atmosphere. The properties were evaluated in this study through metallographic observations, tensile tests, high-temperature oxidation tests, and area-specific resistance (ASR) measurements. The phases and microstructures were characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that high density leads to improved oxidation resistance and electrical performance, with higher-density specimens exhibiting better oxidation mass gain and ASR values than lower-density specimens. The addition of La element improves the mechanical properties, antioxidant properties, and electrical properties of the material, and the addition of La element reduces the ASR of the specimen from 44.16 to 31.18 mΩ ∙ cm². The mechanical properties and oxidative mass gain of the specimen with low Si content are better than those of the specimen with high Si content. When the Si content is reduced from 0.7 to 0.1%, the ASR of the specimen decreases from 57.471 to 44.161 mΩ ∙ cm².</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"670 - 686"},"PeriodicalIF":0.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of Si3N4–NbN Composite Powders","authors":"O. M. Myslyvchenko,&nbsp;R. V. Lytvyn,&nbsp;I. A. Polyakov,&nbsp;I. V. Kud,&nbsp;R. M. Mediukh,&nbsp;L. A. Krushynska,&nbsp;O. B. Zgalat-Lozynskyy","doi":"10.1007/s11106-025-00488-y","DOIUrl":"10.1007/s11106-025-00488-y","url":null,"abstract":"<p>Technology for in situ synthesis of superfine Si₃N₄–NbN composite powders without the need for subsequent milling via solid-state interaction in the Si₃N₄–Nb reaction mixture was developed for the production of nitride ceramics by spark plasma sintering and hot pressing. The regularities of solid-state interaction during vacuum heat treatment of the β-Si₃N₄–27.4 wt.% Nb reaction powder mixture, calculated for the synthesis of higher niobium nitride by the 4Nb + Si₃N₄ = 4NbN + 3Si reaction, were analyzed. The interaction of the mixture components was studied under isothermal holding for 1 h at 1000, 1100, 1200, 1300, and 1400°C. Solid-state interaction with Si₃N₄ was found to occur at 1000°C, resulting in the formation of a nitrogen solid solution in niobium (α-Nb). At 1100°C, the formation of lower nitride Nb₂N and lower silicide Nb₅Si₃ was observed. An increase in the temperature to 1200 and 1300°C led to a greater amount of Nb₅Si₃, whereas the amount of Nb₂N hardly changed. At 1400°C, the product contained a mixture of γ-Nb₅Si₃ and NbSi₂ silicides, while the lower nitride was absent. Thermodynamic calculations confirmed that the formation of higher niobium nitrides under these vacuum heat treatment conditions was thermodynamically unfavorable. Based on the established structural and phase regularities of solid-state interaction in the Si₃N₄–Nb mixture, a two-stage synthesis process was developed. This process was implemented in a single cycle consisting of vacuum heat treatment at 1000°C, followed by nitriding at 1200 and 1300°C. Nitriding at 1300°C yielded a powder composed of Si3N4 and a mixture likely containing three higher niobium nitrides of different polymorphic modifications. Using the developed synthesis process, experimental batches of Si₃N₄–20 vol.% NbN and Si₃N₄–10 vol.% NbN composite powders were produced. Analysis of the experimental batches showed that all synthesized powders possessed the required phase composition and were superfine. The particle size of the Si₃N₄–20 vol.% NbN powder ranged from 400 nm to 9 μm and that of the Si₃N₄–10 vol.% NbN powder ranged from 1.5 to 5 μm.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"601 - 609"},"PeriodicalIF":0.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of the Microstructure and Phase Composition of the Al–15 wt.% Fe Powder Alloy During Its Consolidation","authors":"S. Yu. Teslia,&nbsp;A. M. Stepanchuk","doi":"10.1007/s11106-025-00491-3","DOIUrl":"10.1007/s11106-025-00491-3","url":null,"abstract":"<p>The evolution of the microstructure and phase composition of the Al–15 wt.% Fe powder alloy during pressing and sintering was studied. The structure of the starting powders, produced by melt atomization, was found to be multiphase and consisted of a solid-solution α-Al matrix and Al₆Fe and Al₁₃Fe₄ intermetallic compounds. The presence of the metastable Al₆Fe phase was attributed to the high cooling rates in the powder production by melt atomization. The sintering of green compacts prepared from the alloy powders involved negative shrinkage, which increased with higher sintering temperature, holding time, and compaction pressure for the starting samples. A potential cause of this phenomenon is the transformation of the metastable Al₆Fe phase into Al₁₃Fe₄, having a greater specific volume. Under solid-state sintering conditions at 500–600°C, the structure of the compacted samples remained fine-grained and included both the metastable Al₆Fe and stable Al₁₃Fe₄ phases. This promoted favorable conditions for achieving enhanced mechanical properties through the precipitation strengthening effect. In contrast, sintering at 800°C, accompanied by the formation of a liquid phase, led to recrystallization and formation of predominantly coarse Al₁₃Fe₄ crystals. This microstructural evolution diminished the strengthening effect provided by fine intermetallic phases. It was demonstrated that a sintering temperature of 600°C was optimal for retaining the metastable Al₆Fe phase in the alloy structure, allowing its transformation to be avoided and ensuring a controlled level of shrinkage during consolidation. The results may be useful for optimizing the technology for producing Al–Fe-based components with improved mechanical properties.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"63 11-12","pages":"630 - 639"},"PeriodicalIF":0.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144929426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}