Кафедра теоретичних основ металургійних процесів (ДМетІ)

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ENG: Department of Theoretical Foundations of Metallurgical Processes (Dnipro Metallurgical Institute, DMetI)

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High-Entropy Alloys. A New Concept for the Design of Innovative Structural Materials
(Ukrainian State University of Science and Technologies, Dnipro, 2026) Kamkina, Liudmyla V.; Proidak, Yurii S.; Mianovska, Yana V.; Guba, Roman M.; Bezshkurenko, Oleksii G.
ENG: Modern technologies require state-of-the-art materials that meet their conditions, regardless of operating conditions. Alloys with high entropy can replace traditional materials, work under impacts, dynamic loads, elevated temperatures, etc. These alloys are used for the manufacture of tools, molds, dies, mold casting in parts that require high strength, resistance to oxidation and wear, can also be used in environments with high corrosion resistance parameters (plumbing, marine conditions), in aggressive conditions and in the chemical industry. High entropy alloys are quite easy to investigate and control, and can be obtained by the same methods as traditional alloys, such as: casting, rapid melt quenching, film sputtering, electrolysis, and mechanical alloying. Electroslag remelting (ESD) can greatly improve the purity, hardening structure, and transverse mechanical properties of steel. However, the increasing demands on the mechanical properties of steel are prompting metallurgists to make more efforts to eliminate defects in steel microstructures such as shrinkage and segregation. The combination of directional crystallization technology with electroslag melting technology effectively eliminates macrosegregation in the cast ingot through a shallow molten metal bath controlled by directional crystallization. Increasing the strength of alloys can be achieved either by alloying a solid solution (elements in the internodes) or by isolating the solidification phases or artificially introducing microparticles. Curing phases (carbides, nitrides, carbonitrides, intermetals) can be endogenous (formed from elements introduced into the melt in a liquid state or during its solidification and subsequent cooling) or exogenous (usually introduced into the melt just before crystallization begins, and there is also an increase in size and deterioration in the distribution of solidification phases.
Influence of Ice Structure on Vitability of Frozen Sand-Water and Sand-Clay Mixtures
(Dnipro University of Technology, Dnipro, Ukraine, 2024) Solonenko, Liudmyla I.; Uzlov, Kostiantyn I.; Kimstach, Tetiana V.; Mianovska, Yana V.; Yakymenko, D. Yu.
ENG: Purpose. To establish influence regularity of sand, water and clay preparation conditions on vitability of frozen mixtures made from combinations of these components and to increase the castings quality in foundries, as well as to improve technologies for artificial freezing of soils for underground constructions. Methodology. In this research, sand, clay, and water are used. Ice quality is estimated visually after water freezing at -15 °C in glass tubes. Frozen mixtures’ vitability at -15 °C is studied on beam-type samples. As indicators of survivability, the time to 1 mm bending of samples on supports and the time to their destruction are accepted. The time is recorded with a stopwatch, the temperature with an alcohol thermometer, the mass with electronic scales and the deflection arrow with a clock-type indicator. Findings. The presence and amount of water-soluble impurities in rare water significantly influence the nature, size and distribution of gas bubbles in ice, as well as frozen sand-water mixtures vitability. Frozen mixtures’ survivability increases with water content in them increasing, and, for sand  water mixtures, survivability is maximum if ice has a homogeneous structure. Among mixtures with clays, the mixture with non-swollen kaolin clay has the greatest vitability. Regarding survivability, recommendations for manufacturing products from frozen foundry mixtures have been developed. Originality. For the first time, deformation change kinetics (bending arrows) under the influence of beam-type samples’ self-mass from mixtures of quartz sand and water and quartz sand, clay and water frozen at -15 °C, which have been previously prepared in different ways, have been investigated. Insights into the influence of various factors and ice quality on the vitability of frozen mixtures have been further developed. Practical value. The obtained results can be useful for expanding ideas about natural frozen soils’ behavior during their cyclic temperature changes, soils artificially frozen during mine shafts elaboration, escalators’ and junctions’ tunnels, etc. when constructing subways. In foundries, the developed recommendations will reduce technological losses and will improve casting quality made using frozen casting molds and cores from sand-water or sand-clay-water mixtures, castings’ patterns and their pouring systems from sand-water mixtures.
Regulation of Carbon and Phosphorus Content in Manganese Alloys when Processed in an Oxidizing Gas Environment or Oxide System
(Ukrainian State University of Science and Technologies, Dnipro, 2024) Velychko, K. A.; Mianovska, Yana V.; Kamkina, Liudmyla V.
ENG: Purpose: Determination of rational methods for reducing the carbon and phosphorus content in manganese alloys. Research methodology: thermodynamic calculations and experimental studies of decarburization and dephosphorization of a high-phosphorus manganese alloy. Research materials: As a high-carbon ferromanganese with a high phosphorus content, an associated metal (manganese alloy) obtained during the production of low-phosphorus slag at the Nikopol Ferroalloy Plant was used. Rolling scale was used as an oxidant (composition, wt. %: FeO – 59.5; Fe3O4 – 38.9). Research results: The features of dephosphorization of manganese alloys were considered. According to the adopted “classical” technology, a useful product of dephosphorization of manganese concentrates is manganese slag with a low phosphorus content. Oxidation of phosphorus dissolved in the metal can occur as a result of its interaction with oxygen in the gas phase, while the oxidation of this slag, the higher its basicity, the greater the probability of phosphorus oxidation. Considering the basicity of the slag, the higher the FeO content in it, the better the conditions for removing phosphorus from the metal. The process of dephosphorization of the associated metal includes the oxidation of phosphorus, the binding of phosphorus oxide into strong compounds (phosphates) and their transition to the slag phase. Scientific novelty: The composition of the associated metal includes silicon, which has a much higher affinity for oxygen than phosphorus; Then, naturally, it will first be oxidized with the formation of silicon oxide with a melting point much higher than the temperature of experimental studies. Practical significance: The results obtained show that when oxidizing the associated metal with iron scale at a specific consumption of 114 kg/t of metal, the total degree of extraction: silicon 88.16%, phosphorus 71.03%. At the same time, the manganese content in the metal decreased by 6.48% due to the reduction of rolling scale.