8th International Materials Science Conference HighMatTech-2023
October 2-6, 2023 Kyiv, Ukraine
Metals and Alloys
Head:
Prof. Yuriy Plevachuk
Head of Research & Development Department at Ivan Franko National University of Lviv Ukraine
Yuriy Plevachuk is Professor of the Metal Physics Department and Head of Research & Development Department at Ivan Franko National University of Lviv, Ukraine. He received his Ph.D. degree in molecular physics “Experimental investigations of liquid-liquid equilibrium in metal and semiconductor liquid alloys” (1995) and Doctor of Science degree in Metal Physics “Macro- and microsegregation in the monotectic and eutectic metal melts” (2012) from Ivan Franko National University of Lviv. He was a lecturer at Lviv Polytechnic National University and carried out mobility activities for teaching in the frame of the ERASMUS+ Program at the University of Miskolc, Hungary.
Current subjects of his research are thermophysical properties of liquid metals and alloys; correlation between structure and structure-sensitive characteristics; critical phenomena and phase transitions in metal alloys. He has received several awards among which the IUPAC Poster Prise at 12th Inter. Conference HTMC-XII. He is the author or co-author of more than 150 scientific papers in refereed journals, 5 books and 3 book chapters. Professor Plevachuk is the associate editor of Journal of Physical Studies.
Keynote speaker:
D.Sc., Prof. Peter Svec
Vice-Director and Senior researcherInstitute of Physics, Slovak Academy of Sciences
Peter Svec (Sr.) graduated in Solid State Physics from the Faculty of Electrical Engineering, Slovak University of Technology, Bratislava in 1979, PhD in Solid State Physics in 1986, D.Sc in 2003. Since 1979 he is researcher, senior researcher and vice-director (2011-2019) at the Institute of Physics, Slovak Academy of Sciences. Research focused on physics of metals, especially on formation and phase transformations of metal-metalloid glassy systems, high-resolution investigation of atomic structure & thermodynamics of disordered and nanostructured systems by electron microscopy methods, micromechanisms of nanocrystal formation, quantitative thermodynamic analysis of transformations from metastable states.
He is member of the International Advisory Committee for Rapid Quenching, member of Slovak Learned Society, member and vice-chair of IUPAP Commission C10 on Solid State Physics, holder of State Award, Slovak Patent Office Award and others.
Speakers:
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H3-KK6320 |
Phase diagram of the Al–Ti–Cr system Kostyantyn Korniyenko1, Konstantin Meleshevich1, Anatoliy Samelyuk1, Viktor Sobolev2, Lyudmila Kriklya1 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys of ternary aluminium systems with titanium and d metals of the VI-VIII groups are promising for practical application in various fields of modern technology. Addition of a third alloying element, such as chromium, can improve the low temperature ductility and the oxidation resistance. To develop high-temperature structural and functional materials based on the titanium aluminides alloyed with chromium, an understanding of the phase equilibria in this system is essential.
The alloys of the Al–Ti–Cr system of 25 compositions are prepared from components Al, Ti and Cr (purity of 99.995%, 99.8% and 99.93%, respectively) by arc melting. The alloys are investigated in as-cast and annealed at subsolidus temperatures states by optical microscopy, scanning electron microscopy, electron probe microanalysis, differential thermal analysis, and X-ray diffraction techniques.
Phase equilibria in the Al-Ti-Cr system in the range of 40-100 at.% Al during solidification are represented in this work by specified solidus and liquidus surfaces, a melting diagram as their compilation, a Scheil diagram for solidification as well as isopleths at 50, 60 and 70 at.% Al. Continuous series of solid solutions between betaTi and chromium, solid solutions based on alfaTi, TiAl, Ti2+xAl5-x, TiAl3 (high- and room-temperature modifications), Cr5Al8 (gamma3, gamma2 and gamma1 phases), CrAl4, Cr2Al11, CrAl7 binary compounds and the ternary compound tau take part in phase equilibria. Thirteen invariant four-phase reactions (9 – liquid transition, 3 – peritectic, 1 – eutectic) and three invariant three-phase (two peritectic and one eutectic maxima on monovariant curves) reactions involving liquid take place in the system. Isopleths at 50, 60 and 70 at.% Al demonstrate peculiarities of the phase diagram.
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Kostyantyn Korniyenko |
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H3-KK1558 |
Solidus surface of the Hf–Rh–Ir system Lyudmila Kriklya1, Kostyantyn Korniyenko1, Vasyl’ Petyukh1, Irina Tikhonova1, Anatoliy Samelyuk1, Viktor Sobolev2, Petro Levchenko1 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys of hafnium with refractory metals of the platinum group (rhodium or iridium) are regarded as perspective materials for a number of applications, in particular, as thermal barrier coatings for details of gas turbines and aerospace vehicles, and as cathodes for electrocatalytic hydrogen production. To develop new perspective functional materials based on the Hf-Rh-Ir alloys, an understanding of the phase equilibria is essential, but there were no available literature information about this.
The alloys of the Hf-Rh-Ir system of 16 compositions are prepared from components Hf, Rh and Ir (purity of 99.98%, 99.97% and 99.97%, respectively) by arc melting. The alloys are investigated in as-cast and annealed at subsolidus temperatures (20-50 °C below melting beginning temperatures) states using optical and scanning electron microscopies, electron probe microanalysis, differential thermal analysis, X-ray diffraction and melting points beginning measurements (Pirani-Althertum technique).
For the first time it was established that solid solution based on betaHf, a continuous series of solid solutions between isostructural (Cu type) components iridium and rhodium, isostructural compounds Hf2Rh and Hf2Ir (Ti2Ni type), high-temperature modifications of HfRh and HfIr (CsCl type), HfRh3 and HfIr3 (AuCu3 type), as well as solid solutions based on the compounds Hf5Ir3 and Hf3Rh5 take part in phase equilibria. Solidus surface of this system is formed by seven single-phase surfaces corresponding to solid solutions based on components and above-mentioned compounds, eight tie-line surfaces limiting the two-phase volumes, and two isothermal planes corresponding to invariant four-phase equilibria with participation of a liquid phase (at 1958 °С and 1655 °С).
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Kostyantyn Korniyenko |
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H3-PA2117 |
Application of CALPHAD method for predicting of concentration range of amorphization of transition metals melts Pavel Agraval1, Mikhail Turchanin1, Liya Dreval1,2, Anna Vodopyanova1 1Donbas State Engineering Academy, Ukraine Metallic glasses are attractive due to a set of unique properties, such as mechanical, magnetic, chemical, etc. At present, information about amorphous alloys is available for individual point compositions in the form of data on conditions of production, structure, mechanical and some other physical properties. However, it is often necessary to search for a new alloy in a wider concentration region.
Early, the efficiency of the CALPHAD (Calculation of Phase Diagrams) method to a targeted search for compositions of amorphous alloys has been shown. The method for predicting of amorphization ranges is based on the calculation of diagrams of metastable phase transformations between supercooled melts and boundary solid solutions. Within the framework of the CALPHAD method, the model parameters for thermodynamic properties of liquid alloys and boundary solid solutions were summarized in self-consistent database for the multicomponent Co–Cu–Fe–Ni–Ti–Zr–Hf system. Such database for the multicomponent system is based on a common set of model parameters for boundary binary and ternary systems.
In this report the predicted ranges of amorphization for the quaternary Cu–Ni–Ti–Zr, Cu–Ni–Ti–Hf, and Fe–Ni–Ti–Hf systems are presented on concentration tetrahedrons. For the quinary Fe–Cu–Ni–Ti–Zr, Fe–Cu–Ni–Ti–Hf, and Cu–Ni–Ti–Zr–Hf systems the composition ranges are predicted along sections from four-component equiatomic alloys to pure metals.
It was determined that the predicted composition ranges of amorphszation correspond to a certain total concentration of metals, which are donors (Ti, Zr, Hf) and acceptors (Fe, Ni, Cu) of electrons in the melt. For glass-forming melts of transition metals such a factor is the simultaneous fulfillment of the conditions of xTi+xZr+xHf > 0.2 and xFe+xNi+xCu > 0.2. This factor indicates the important role of the donor-acceptor interaction between components of the glass-forming liquid alloys and its influence on their ability to amorphization.
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Pavel Agraval |
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H3-KP1437 |
Thermokinetics of Recrystallization of Copper Compacts Viktor Solntsev, Gennady Bagluk, Tetiana Solntseva, Kostiantyn Petrash Frantsevich Institute for Problems of Materials Science, Ukraine The mechanisms of copper recrystallization processes, as well as other metals and alloys, are of particular interest in connection with the problems of forming the structure and properties. The dynamics of thermal processes during recrystallization significantly affects the technological properties and the formation of a spatially organized structure.
The study of the thermokinetics of recrystallization of copper compacts was carried out on a solar plant with unilateral radiant heating from the side of the end face of cylindrical samples. To obtain compacts, electrolytic copper powder was used. The samples were pressed in a cylindrical mold with a diameter of 10 mm. Chromel-alumel thermocouples were installed in holes in the depth of the sample and placed lengthwise with a step of 4 mm from one another. The change in the temperature of the reaction system was recorded using a high-speed computerized signal recording system.
The recrystallization process can be viewed as a first order reaction, i.e. the transition from the deformed state to the annealed state with an ideal lattice and is accompanied by a thermal effect. Several stages of recrystallization were found, which corresponds to the known data, but the appearance of traveling thermal waves is observed. By analogy with first-order reactions in the high-temperature synthesis of intermetallic compounds, the appearance of various types of wave processes has been shown. Traveling waves can appear in the system. This can lead to thermal interference and, as a result, there is localization of thermal energy and a sharp increase in temperature in certain areas of the wires deformed during switching, and their ignition. The experimentally observed values of temperature bursts indicate the occurrence of combustion processes in insulating materials. Thus, it is possible to explain the cause of accidents observed during the operation of complex mechanisms with a large number of electrical connections.
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Tetiana Solntseva |
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H3-OZ1653 |
Role of hydrogen in strain aging of ferritic/pearlitic low alloy steel under long-term operation Olha Zvirko, Hryhoriy Nykyforchyn, Oleksandr Tsyrulnyk, Myroslava Hredil, Oleh Venhryniuk, Halyna Krechkovska, Oleksandra Student Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine Long-term operation of structural steels often results in a significant deterioration of initial mechanical properties determining their serviceability [1]. Two main stages of operational degradation of structural steels are commonly considered [2]: strain aging and development of dissipated damages, resulted in metal embrittlement. In the paper, the influence of hydrogen on embrittlement of ferritic/pearlitic low alloy steel on the stage of strain aging was analysed. It is known that hydrogen charging of steels is accompanied by an increase in internal stresses. In this case, it was assumed that plastic deformation will be localized in sites with the highest hydrogen concentration, and strain aging will occur in these locations during subsequent heating of steel after hydrogen charging. The Fe-0.17C-1.5Mn-0.5Si low alloy steel in the as-delivered state and after 36 years of operation was investigated. The specimens were subjected to electrolytic hydrogen charging. Then they were heated to 250 °C and held for 1 hour. Such a procedure enables inducing strain aging in local plastically deformed locations and desorbing hydrogen. The results showed that the steel subjected to the procedure of combining preliminary hydrogen charging with heating was characterized by a significant decrease in fracture toughness and resistance to stress corrosion cracking. The effect was more significant for the long-term operated steel. Embrittlement of the treated steel was confirmed by fractographic analysis of specimens tested for stress corrosion cracking, which revealed intergranular fracture. Such a behaviour of the steel was associated with strain aging of the hydrogen pre-charged metal. It was indirectly shown that hydrogen charging of steels can cause embrittlement by the strain aging mechanism in the dominant sites of hydrogen transport, namely, the grain boundaries.
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Olha Zvirko |
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H3-HK2135 |
Visualization of damage to heat-resistant steel after long-term operation on the main steam pipeline for fractographic signs of its destruction Halyna Krechkovska1,2, Oleksandra Student1, Ivan Tsybailo1 1Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine The influence of operational factors contributes to the occurrence of damage in elements of thermal power equipment with their subsequent fracture. Fractographic analysis has become widely used to assess the technical condition of operated steels, in particular to find out the reasons of the destruction of structural elements. The identified fractographic features allow to establish the current state of thermal power elements.
The low-alloy heat-resistant steel 15Kh1M1F in the initial state and after the long-term operation in main steam pipelines of TPP were studied. To assess the actual state of the operated metal, the following characteristics were used: impact toughness, fracture toughness, fatigue crack growth resistance. Metallographic and fractographic peculiarities of steel were evaluated using SEM.
The quantitative structural indicators that determine the mechanical properties of the steel long-term operated on the steam pipelines include the sizes of grains and carbides in its structure, which increase with more shutdowns of power units. The fractographic sign of cohesion weakening between adjacent grains in operated heat-resistant steel is fragments of intergranular fracture on the fracture surfaces steam pipelines and also on the fracture surfaces of steel specimens after impact and fatigue testing. These intergranular fragments are considered the key sign of steel’s degradation indicating structural changes in it, namely, the precipitation and coagulation of carbides along the grain boundaries, their separation from the matrix to form pores, their further merging and thus initiation of intergranular cracks. It is proposed to use the area of intergranular fragments per unit area of the fracture surface as a quantitative fractographic indicator of the change in its technical condition due to degradation. This fractographic indicator of the metal state is consistent with the mechanical characteristic of resistance to brittle fracture.
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Halyna Krechkovska |
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H3-SV0280 |
Thermodynamic properties of melts Bi-Pr of system Volodymyr Shevchuk, Volodymyr Kudin, Nataliya Podoprigora, Valentina Sudavtsova I.M Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Alloys and compounds of many systems of Bi with d- and f-elements exhibit thermoelectric and magnetic properties. In order to obtain such materials, it is necessary to know their phase diagrams and thermodynamic properties of various phases, especially liquid, because most of them are obtained by melting. The thermodynamic properties of diluted melts with respect to Pr have been studied by the EMF method [1]. According to these data, the first partial enthalpy of mixing is –259.6±2.5 kJ/mol at 1000 K. The enthalpies of formation of intermediate phases Pr4Bi3 and PrBi determined by the method of calorimetry are exothermic (-93.8±2.1 and –100.1±2.1 kJ/mol). The thermodynamic properties of melts of the Bi-Pr system were first investigated by the method of calorimetry at 0 < xPr < 0.3 and T =1310±2 K in this paper. It was established that the first partial enthalpy of mixing of bismuth is -400±28 kJ/mol, which correlates with a similar value for Pr determined by the EMF method. Approximation of our experimental data, taking into account the fact that at хBi=1 ΔН=0, made it possible to calculate the integral and partial enthalpies of mixing in the entire range of concentrations (the minimum integral enthalpy of mixing is −75±12 at xPr = 0.65 at 1310±2 K) . This is consistent with the fact that ΔfН of Pr4Bi3and PrBi compounds is larger in absolute value, as is characteristic of melts with a strong energy of interaction between particles of different atoms. In order to expand the information about the thermodynamic properties of all phases of the Bi-Pr system, we calculated and optimized these parameters using the ideal associated solution model. The activity of the components shows very large negative deviations from ideal solutions. The maximum molar fractions of PrBi and Pr2Bi associates are 0.92 and 0.7, respectively. This confirms high energy of interaction between the heterogeneous atoms at these concentrations and predominant role of associates in them.
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Volodymyr Shevchuk |
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H3-SV0561 |
Thermodynamic properties of melts of Mg–In and Mg–In–Yb systems Dudnik Anton, Volodymyr Kudin, Larysa Romanova, Valentina Sudavtsova I.M Frantsevich Institute for Problems of Materials Science, NAS of Ukraine Data on the thermodynamic properties of various phases and, in particular, the liquid phase, are necessary for the scientifically based development of methods for obtaining the specified materials. Therefore, the purpose of this work are to study by the method of calorimetry the enthalpies of mixing of melts of Mg–In systems in the range of compositions 0 < xMg <0.3 and at Т=961±1K, as well as Mg–In–Yb for the section 1:1 at Т=1281±1K. The thermodynamic properties of the liquid phase of the Mg–In system have currently been studied by various methods and optimized in [1]. A comparison of ΔН determined by us and optimized showed that they agree with each other within the experimental error (ΔНmin=-6.7 and -7.7±0.5 kJ/mol). For the melts of the Mg–In–Yb system in the studied section up to xYb<0.3, it was established that the first partial enthalpy of mixing of ytterbium is -100±8, and ΔНmin= -27.2kJ/mol. This indicates on the formation of ternary associates with a rather large energy of interaction between atoms of different names. The thermodynamic properties of the liquid phases of the Mg–Yb and In–Yb systems are now known. Their ΔHmin=-4.3 at 1016K and –36.5±1.0 kJ/mol at 1350 K, respectively. In recent years, thermodynamic properties of melts of ternary systems have been calculated from similar data for binary boundary subsystems according to the Redlich-Kister-Mujianu model, when the data for the latter are known. We estimated the thermodynamic properties of melts of the Mg–In–Yb system according to this model. According to our calculations, it was established that ΔНmin=-36.5±1.0 kJ/mol at xYb=0.5 of the In–Yb subsystem. ΔG, ΔS of these melts were calculated according to the same model. It was established that ΔGmin=–28.5 kJ/mol, and ΔSmin=–7.9 J/mol·K, the minimums of which also fall on the same limiting subsystem, i.e., the main contribution to the interaction energy between different atoms of melts of the Mg–In–Yb system the contribution of In–Yb subsystem.
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Dudnik Anton |
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Poster session Important.session is online-only and include 5 min presentation in the common conference room and 1 hour of discussion in individual rooms (Zoom) |
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H3-AB1458 |
Surface hardening of Ti6Al4V alloy using high-frequency mechanical impacts Svitlana Voloshko1, Andrii Burmak1, Bogdan Mordyuk1,2, Taras Krasovskyi3, Nataliya Franchik1, Myhailo Vasylyev2 1National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” A comparison of the effects of high-frequency hardening by balls (SMAT) and local high-frequency mechanical impact (HFMI) treatment by an impact element on the mi-cromechanical characteristics and microstructure-phase state of the surface of the Ti6Al4V (VT6) alloy is carried out. The SMAT processing of the sample surface was carried out in the air for 30–240 s with steel balls of 2 mm in diameter, the movement of which was induced by an ultrasonic sonotrode oscillating at a frequency of ~20 kHz. The results were compared with the HFMI processing by cylindrical steel striker of 5 mm in diameter under comparable time regimes. The mechanical characteristics were determined based on the instrumental indentation data, and the microstructure parameters and the presence of the oxide phases on the surface were determined by X-ray diffraction analysis. The features of the microhardness changes and XRD based data regarding the macrostresses, crystallite size, and microstructure-phase state after high-frequency impact treatments of various ultrasonic excitations were established.
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Andrii Burmak |
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H3-ST1410 |
Bioresorbable powder materials based on Mg-Mn-Zn Serhii Teslia, Tetiana Soloviova, Mykhailo Vterkovskyi, Vitalii Sheremet, Petro Loboda Igor Sikorsky Kyiv Polytechnic Institute, Ukraine Bioresorbable materials are a breakthrough solution in biomaterials science for different orthopedic surgeries. Due to controlled resorbed, the material is removed from the body after the overgrowth of the bone tissue. Powder magnesium alloys have found wide applications for creating bioresorbable fixing pins. Pure magnesium dissolves quickly and forms a large amount of hydrogen, which negatively affects the human body. To increase corrosion resistance, alloying elements, usually rare earth materials, are added to magnesium. The aim of the work was to study the processes of mixing and consolidation of Mg-Mn-Zn. The initial powders (Mg-1 wt. % Zn, Mg-1 wt. % Mn, Mg-1 wt. %; Mn-1 wt. % Zn) were mixed in a shaker mixer for 10, 15, 20, and 25 hours without the addition of mixing agents. The quality of mixing was assessed using microstructural analysis and EDS elements mapping. Densification was carried out by uniaxial and cold isostatic pressing, for 200-600 MPa. Green samples were sintered at 600 °C for 2 h in an argon atmosphere. In the first stage of mixing, an increase in the quality of mixing is observed. But an increase in time above 20 h leads to the formation of conglomerates, which reduces the uniformity of the alloying elements distribution. Due to the high plasticity of magnesium, even at 400 MPa, it is possible to obtain almost 100% material density, both by uniaxial and isostatic pressing. The densification method significantly affects the final microstructure of the alloys. When uniaxial pressing was used, the pores have an angular shape with an average size of 20 µm. After CIP, there are practically no pores in the structure of the material; single pores have a spherical shape of less than 5 µm. It was found that increasing the mixing time does not linearly change the uniformity of the alloying distribution. The use of CIP for densification of magnesium alloy powders is more preferable as it provides low porosity and alloying uniformity by volume.
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Serhii Teslia |
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H3-NU1736 |
The thermochemical properties of ternary Ag–Eu-Sn liquid alloys Natalia Usenko1, Michael Ivanov2, Natalia Kotova1 1Taras Shevchenko National University, Ukraine Ternary alloys of the Ag–Sn–Eu system may be of practical interest for several reasons. For example, ternary alloys of europium with silver and p-metal have interesting magnetic properties. Besides, binary and ternary alloys containing tin and silver are widely used as lead-free solders and the presence of a rare-earth metal in solders refines their microstructure, melting behaviour and mechanical properties. The lanthanides also improve the corrosion properties of such solders, reducing their corrosion rate. So, thermodynamic data for the Ag–Sn–Eu system may be useful, giving the possibility of calculating phase equilibria to find the compositions with the best technological efficiency. The present investigation is a prolongation of a series of systematic studies of ternary alloys of the transition metal–rare-earth metal–p-metal family. The enthalpies of mixing in liquid alloys of the ternary Ag–Sn–Eu system were determined over a wide range of concentrations by means of isoperibolic calorimetry in the temperature range from 1313 to 1373 K. The partial enthalpies of each component of the ternary system were measured along the following sections: the partial enthalpy of silver along the section with xSn/xEu = 0.72/0.28 up to silver content of about xAg = 0.2 at 1373 K; the partial enthalpies of tin along three sections (xAg/xEu = 0.31/0.69, 0.50/0.50 and 0.70/0.30) up to xSn = 0.35 at 1373 K; the partial enthalpy of europium along the section xAg/xSn = 0.50/0.50 up to xEu = 0.25 at 1313 K. The enthalpies of mixing in the liquid Ag–Sn–Eu alloys show exothermic effects, being more pronounced in the vicinity of the Sn–Eu binary constituent. The minimum value of the integral enthalpy of about –60 kJ/ mol is observed in the composition region of the congruently melting Eu2Sn phase.
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Natalia Usenko |
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H3-OM1256 |
Properties of nickel powders obtained by reduction in moving layers Olena Makarenko, Petro Radchenko, Olha Hetman, Tetyana Babutina, Anatolii Samelyuk Frantsevich Institute for Problems of Materials Science of NASU, Ukraine Nickel powders are usually produced by hydrogen reduction of nickel oxide in stationary furnaces in a fixed layer. In this case, it is necessary to ensure the rapid removal of water vapor from the reduction zone by increasing hydrogen consumption. A promising method for obtaining nickel powders is the reduction of nickel oxide in hydrogen in moving layers in a rotary furnace. The movement of powder layers during reduction ensures continuous contact of oxide particles with hydrogen, rapid removal of water vapor from the reaction zone, and establishment of a reduction regime close to kinetic. The aim of this work was to determine the properties of nickel powders obtained by reduction in a rotary furnace.
Nickel oxide was obtained by decomposition of basic nickel carbonates at 550°C for 1 h. The reduction of nickel oxide with hydrogen was carried out at 500 and 600°C for 2 h. The dispersity of the powders was estimated from the specific surface determined by the thermal desorption of nitrogen. The oxygen content in nickel powders was determined by gas chromatography. The morphology and particle size of the nickel powders were explored with a scanning electron microscope.
Nickel powders were produced from nickel oxide with a specific surface area of 25 m2/g. Nickel metal powders are highly porous agglomerates consisting of submicron nickel particles. The sizes of agglomerates are in the range from 5 to 125 microns. The powders have a high specific surface were 5,8 and 3,5 m2/g at reduction temperatures of 500 and 600 °C, respectively. The nickel agglomerates formed in the rotating chamber have a smooth rounded shape. The bulk density of the Ni powders was 1,3 g/cm3, the oxygen content was 0,06%. Nickel powders are actively compacted during sintering. The compaction factor of samples at a sintering at 1250 °C for 20 min depends on the specific surface of the powders and is 0.8 and 0.6 for powders with a specific surface of 5,8 and 3,5 m2/g, respectively.
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Olena Makarenko |
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H3-PK2110 |
Experimental bench tests on the corrosion resistance of construction materials and environmental safety for the cooling system of a nuclear power plant with biocides water treatment Pavlo Kuznietsov1,2, Olga Biedunkova1 1National University of Water and Environmental Engineering, Ukraine Biological pollution creates significant obstacles in the operation of power plants' technical water supply cooling systems (SCS). To minimize biological pollution, methods of corrective treatment with biocides are implemented. While these biocides effectively prevent fouling of the cooling system, they can also adversely affect the environment and structural materials. By evaluating structural materials' corrosion resistance and biocides' environmental safety for the cooling water during biocide treatment, any potential issues can be identified and addressed before they become a safety or operational concern. The paper presents the results of bench tests of the corrosion resistance of structural materials SCS, corrosion aggressiveness of the biocides: sodium hypochlorite NaClO and 2, 2-dibromo-3-nitriloropionamide (DBNPA), and the results of measurements of the concentration of biocides and their decomposition products to assess compliance with environmental standards when discharging return water when applying from biocides treatment. The cooling water SCS of the Rivne NPP (Nuclear Power Plant) was chosen as the research object. Bench corrosion tests were carried out using samples of corrosion indicators from materials: steels Ст20, 08Х18Н10Т; copper alloy МНЖ-5-1 and aluminum, which are defined as analogs of structural materials of the technical water supply system of the Rivne NPP. The conditions of operation of the technical water SCS of the Rivne NPP were simulated on the test bench, and corrosion rate measurement was carried out by the gravimetric method.
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Olga Biedunkova |
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H3-IV1159 |
Structural sensitivity of the wear resistance of Armco-iron at friction by quasistatic and dynamic loading Konstantin Grinkevych, Yurii Podrezov, Alex Golubenko, Igor Voskoboynik, Nick Iefimov Institute for Problems in Materials Science NASU of І.М.Fratsevich, Ukraine On the example of Armco-Fe, the structural sensitivity of wear resistance both of the quasistatic and dynamic friction loading was studied. Armco-Fe samples with different grain sizes, from ~21 µm to ~560 µm, were obtained. Tribological properties and microhardness were studied. Wear tests were carried out on the tribodynamic complex (ATKD). Reciprocating sliding movement of an indentor from 52100 steel ball vs the polish surface of flat specimens was carried out. Microhardness was determined on PMT-3 by Vickers indenter under load P=0.5 N.
The structural sensitivity of the hardness (H) and wear resistance (W) under static loading shows three sections. In the area of small grains, where the size of the indent or contact spot together with the plastic zone around them turns out to be larger than the grain size, the experimental dependences follow the Hall-Petch law: W, H~d⁻¹⁄².
In the region of large grains, where the plastic zone under the indent fits into one grain, there is no sensitivity to the grain size. The anomalous nonmonotonic dependence located in the middle area, where the grain size is comparable to the size of the plastic zone. It can be explained by the interaction of dislocations in the plastic zone with the grain boundaries, which either limit the movement of dislocations, forming clusters, or on the contrast, accelerate the process of their propagation due to the triggering of Frank-Reed sources near the boundaries.
In case dynamic loading the wear resistance demonstrates similar structural sensitivity, but the relative influence of the grain size is much smaller. In this instance the intensive deformation processes took place in the subsurface layer with the formation of dislocation substructure. Such effect is much stronger on the wear resistance than the effect of the boundaries.
The likeness of structural sensitivity of the studied mechanical characteristics testifies the uniform deformation mechanisms determining the grain size effect on H and W.
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Konstantin Grinkevych |
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H3-NK1342 |
The enthalpies of mixing of ternary Al–Ce–Co liquid alloys Natalia Kotova1, Natalia Usenko1, Michael Ivanov2 1Taras Shevchenko National University, Ukraine For aluminium-rich alloys of the Al–Ce–Co ternary system, amorphous alloys have been obtained, which are characterized by high specific strength and high resistance to corrosion. Persistent efforts to synthesize bulk Al-rich amorphous alloys have been made for over a decade. The process of metallic glass formation and the prediction of new glass compositions are ongoing areas of intensive research. One of the necessary conditions for the successful prediction of such compositions for each glass-forming system is the existence of a thermodynamic description of the liquid phase, which is directly involved in the formation of amorphous metallic glass. The experimental data on enthalpies of the formation of liquid alloys are an important part of obtaining such a description. The present investigation is a prolongation of a series of systematic studies of ternary alloys of the transition metal–rare-earth metal–p-metal family. The enthalpies of mixing in liquid alloys of the ternary Al–Ce–Co system were determined over a wide range of concentrations by means of isoperibolic calorimetry at 1823 K. The partial enthalpies of each component of the ternary system were measured along the following sections: the partial enthalpies of aluminium along the sections with xCe/xCo = 0.77/0.23 and 0.35/0.65 up to aluminium content of about xAl = 0.2; the partial enthalpy of cerium along the section xAl/xCo = 0.76/0.24 up to xCe = 0.3; the partial enthalpy of cobalt along the section xCe/xAl = 0.70/0.30 up to xCo = 0.22. The enthalpies of mixing in the liquid Al–Ce–Co alloys show exothermic effects, being more pronounced in the vicinity of the Al–Ce binary constituent. The minimum value of the integral enthalpy of about –50 kJ·mol–1 is observed in the composition region of the congruently melting at high temperature Al2Ce phase.
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Natalia Kotova |
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H3-VM1404 |
The iron-carbon system. Eutectic crystallization involving hyper-cementite carbide. Vladyslav Mazur Igor Sikorsky Kiev Polytechnic Institute, Ukraine White cast irons are successfully used in foundry production for parts that operate under static conditions. The brittle cementite matrix limits its use in impact applications. This relatively inexpensive material can be used under shock loads if we invert the eutectic constituent. Thus, the purpose of this work is to develop the theory and technology of inverted eutectics crystallization. The methods used include light metallography with a Jenaphot 2000 (Carl Zeiss, Jena, Germany) and differential scanning calorimetry with a STA 449C “Jupiter” (Netzsch Gerätebau GmbH, Germany). A simple technology of thermal cyclic processing of the melt has been developed in order to generate significant super-cooling, which causes the formation of inverted plate-like eutectics with a matrix of transformed austenite and carbide reinforcing phases. The features of the kinetics of nucleation and growth of inverted plate-like eutectics based on metastable carbide (Fe7C3+γ) (in microscopic and thermal (DSC) imaging) have been established. On the basis of the results of experiments, the schematic diagram of the metastable phase equilibrium in the subsystem Fe-Fe3C-Fe7C3 has been provided. With the help of the diagram, it is possible to explain without contradiction all the phase transformation in a subsystem. This work lays the foundation for the theory and technology of a new cheap natural composite with a matrix of transformed austenite and Fe7C3 carbide reinforcing phases.
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Vladyslav Mazur |
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H3-OB1142 |
Peculiarities formation of welded joints under the external electromagnetic influence Sergei Maksimov, Olena Berdnikova, Olena Prilipko, Tetiana Alekseenko E.O. Paton Electric Welding Institute National Academy of Sciences of Ukraine Controlling the movement of liquid metal by selecting the parameters of an external electromagnetic effect makes it possible to change the conditions of dynamic equilibrium of the weld pool and, as a result, the formation of a weld.
Magnetic process control has advantages over mechanical control methods, since it is carried out without contact with the welding zone.
The study of processes leading to a decrease in the concentration of defects in metals, recombination of dislocations, polygonization, recrystallization, defect healing, etc., is an urgent task for technologists.
The work aims to investigate the effect of EEW during welding on the microstructure parameters, phase composition, microhardness, strength properties and crack resistance of the metal of welded joints of low-alloy steel.
Microstructure studies were carried out by light, scanning, and transmission electron microscopy. Mathematical modelling was carried out to optimize the research efficiency. The developed computer application implements the idea of sequential calculation of quantities, where the value of the welding current and the current in the inductor is selected by the researcher.
It has been established that the most effective in welding low-alloy steel with EEW is using transverse magnetic fields. This ensured the formation of the most acceptable structure with a uniform level of microhardness both in the weld metal and in the HAZ sections and a noticeable refinement of the structure. The influence of structural factors at the dislocation level on local internal stresses, which determine the deformation localization zones in the structures of the upper and lower bainites in the deposited metal, is analyzed. The conditions for obtaining high-quality welded joints in the welding of low-alloy steels, which ensure their strength and crack resistance, are established.
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Olena Prilipko |
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H3-IF1252 |
Phase transformations in the Ti-Fe-Sn system Iuliia Fartushna, Maryna Bulanova, Kostyantyn Meleshevych, Anatolii Sameliuk, Iryna Tikhonova I.M. Frantsevich Institute for Problems of Materials Science, Ukraine Heusler intermetallic compounds are a class of very promising materials with wide potential applications due to various useful properties. Fe-based Heusler compounds noteworthy magnetic properties and are also considered as highly attractive candidates for thermoelectric materials. The magnetic properties of Fe3Sn compound are also interesting. In addition, ultrafine eutectics with high strength and plasticity are formed in the Ti-Fe-Sn system and in multicomponent systems based on it. Thus, the ternary Ti-Fe-Sn system is of practical and scientific interest.
Bulk metals of Ti-99.98%, Fe-99.9%, Sn-99.9995% were used to produce the ternary alloys. Alloys were prepared by arc-melting under a purified argon atmosphere using a non-consumable tungsten electrode on a water-cooled copper hearth. The as-cast samples were homogenized at 1000°C for 2 months in quartz tubes in a SNOL 7.2/1100 muffle furnace. The as-cast and annealed alloys were then examined by scanning electron microscopy, electron probe microanalysis, differential thermal analysis, and X-ray diffraction analysis.
In present work the phase equilibria in the Ti-Fe-Sn system were studied for the first time upon crystallization and at 1000°C in a whole concentration region. The liquidus and solidus projections, the Scheil diagram and isothermal section at 1000°C were constructed. It is shown that the half-Heusler FeTiSn phase melts congruently, while the Fe2SnTi (full-Heusler) and FeSnTi2 form by peritectic reactions. Only Heusler Fe2SnTi phase has a wide range of homogeneity from 48 to 67 at.% Fe.
Three binary phases Ti5Sn3, Ti6Sn5 and TiFe2 have extended homogeneity ranges in the ternary system. TiFe2 dissolves 13 at.% Sn. The solubility of Fe in Ti6Sn5 was measured to be 21 at.%. Ti5Sn3 dissolves 14 at.% Fe forming an interstitial solid solution, which orders at composition Ti5FeSn3. This ordered phase Ti5FeSn3 has a Hf5CuSn3 type structure.
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Iuliia Fartushna |
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H3-AO1637 |
Molecular dynamics simulation of an early stages of interfacial amorphization in Ni/Ti system Sergii Konorev, Yaroslav Sokur, Ivan Kruhlov, Andrii Orlov National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine NiTi intermetallic alloys are promising for application in biomedicine [1] and microelectromechanical systems (MEMS) [2] due to their pronounced shape-memory effect, high work output, and good corrosion resistance. Though it is known that the growth of the intermetallic phases occurs through the formation of an amorphous phase [3], currently there is a lack of understanding of where this phase starts to form as well as the factors affecting this process. Present work is focused on studying the nucleation kinetics of NiTi amorphization by computer simulations.
To address this goal, we applied computer simulation using molecular dynamics (MD) approach. LAMMPS software and modified embedded-atom method (MEAM) potential for Ni-Ti system [4] were used. The model structure consisted of bi-, four- and six-layered stacks of alternating fcc Ni and hcp Ti (total number of atoms in system was up to 60000). The system was relaxed using energy minimization at simulation temperature followed by the heating to 900 K with exposition up to 105 steps MD (10-9 s) .
It was found that the processes of lattice distortion and nucleation at the interfaces are spontaneous and have a thermally activated nature. The probability of nucleation as well as the time of its formation increased with increasing the heating rate, which is most likely associated with the interfacial stresses arising due to the lattice mismatch and difference in CTE of Ni and Ti more than 1.5 times. At high heating rates (200 К/1000 steps MD), the stresses cannot fully redistribute and relax through the system, thus they act as a driving force for the nucleation. Moreover, the kinetics of nucleation is the higher, the farther from the outer surface the interface is located. It was also revealed that the nucleation onset is affected by the combination of the Ni and Ti crystal faces with different atomic packing density, as well as the number of the interfaces in the model.
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Yaroslav Sokur |
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H3-VT0105 |
Electrochemical studies of the dental implants from titanium and titanium alloys Victor Talash1, Yuliia Rudenko1, Valerii Nespryadko2, Valerii Los2, Maskim Pavlenko3, Valerii V. Los3 1Frantsevich Institute for Problems of Materials Science, NAS of Ukraine A lot of metals and alloys are used in the manufacture of dental prostheses (implants). Unfortunately, corrosion processes take place in the oral cavity on the surfaces of dental materials with the formation of products that can have an individual effect on the particular human organism. Determination of the implants’ surface resistance to dissolution in the oral cavity environment (electrolytes) has practical clinical significance.
The implant material composition is a decisive to prevent of it dissolution and complete corrosion protection. Each implant has its own specific corrosion behaviour. To increase the stability of titanium implants and increase the biotolerance and biocompatibility of the implant with the surrounding bone, it is recommended to carry out preliminary anodic polarization.
Electrochemical corrosion studies were performed by potentiodynamic polarization curves method in 3% NaCl solution for investigation of possible anodic dissolution of the implants from titanium (99.99%) and titanium alloys. The platinum counter electrode and Ag/AgCl as the reference were used. The temperature was 310 K for all experiments.
If there are at least two implants of different nature, the potential difference of the galvanic pairs can be 0.2-0.3 V max. The alloy VT-6 (Ti – 89.03%; Al – 6.85%; V – 4.13%) has an insufficient length of the corrosion-resistant interval potentials (0.2 V). This can cause its dissolution products (V and Al ions) to enter the human body, which have a negative effect if the MPC is exceeded.
The obtained data indicate high corrosion resistance of pure titanium and its alloys with Nb and Si. The previous anodic polarization of these implants in the range from a stationary potential to 1 V contributes to the creation of a nanofilm (Ti₂O, TiO and Ti₂O₃, thickness up to 20 nm), which tightly adheres to the base and does not crack during long-term operation, and leads to significantly increase their life time.
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Victor Talash |
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H3-MS0351 |
Features of obtaining high-entropy CoCrFeNiMn1-x alloys by the powder metallurgy method and their mechanical properties. Maria Saviak1, Angel Vicente Escuder2, Elizaveta Klytskina2, Vicente Amigó Borrás2 1Institute for Problems of Material Sciences NAS of Ukraine In the work, a series of high-entropy CoCrFeNiMn(1-x) alloys (where x varies from 0 to 1) was obtained by mixing the initial metal powders in a mixer, followed by compaction of the powders under a pressure of 1000MPa, followed by sintering at 1200-1300С in a vacuum. The formation of high-entropy alloys after sintering is evidenced by X-ray and significant plasticity, which reaches 5.8% during flexural strength tests. It is shown that the processes of consolidation of CoCrFeNiMn(1-x) alloy powders are influenced by both the percentage of manganese and the sintering temperature. Evaporation of alloy components and different diffusion coefficients of alloy components lead to volume growth of samples in the entire range of manganese concentrations (0-20 at%) at temperatures of 500-800C, and the high activation energy of sintering of the CoCrFeNiMn(1-x) alloy does not allow obtaining dense samples even when the temperature of sintering is increased to 1300C. Samples with 5-10at% manganese had the highest density of 86%. Alloys with 5 at.% Mn showed the greatest strength and ductility. The alloy with 10 at.% Mn had the highest modulus of elasticity .
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Maria Saviak |
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H3-OM1330 |
The rational constructional and technological parameters determination method for powder materials forming processes Anatoliy Mikhailov1, Yevgenii Shtefan2, Oleg Mikhailov1 1Institut for Problems of Material Sciences National Academy of Science of Ukraine Problem statement and objective.
One of the perspective methods products manufacturing is the powder materials shape formation processes. The effective deformation schemes design and rational technological powder specimen parameters determination is possible on the base of preliminary computer modeling. So, one of the main problems in the powder metallurgy technologies design is the mathematical and computer modeling methods development for the corresponding products shape formation processes.
Methods
The main research method is based on mathematical modeling of the shape formation processes of dispersed materials in the regime of plastic and elastic-plastic deformation of the solid phase with the use of projection-grid methods and computer technologies. Computational experiments are used for rational technological schemes determination of powder materials forming processes.
Main results and Conclusions
The mathematical model of shape formation processes of structurally inhomogeneous porous materials is developed. On the basis of the generalized model of plastic deformation of powder and porous materials processes and by the finite elements method the technique of rational constructive-technological parameters determination for powder metallurgy technologies is developed.
The practical use of the proposed methodologies made it possible to determine: - the regularities of the different moduli material layers interaction during stamping of bimetallic blanks with an inner cone-shaped surface; - the porosity distribution over the workpiece volume at the final stage of radial extrusion of the bushings with an internal flange; - the effect of powder material decompaction during reverse extrusion of cylindrical products.
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Yevgenii Shtefan |
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H3-OK2018 |
Structure and properties of liquid quenched Al₄CoCrCuFeNi high-entropy alloy Oleksandr Kushnerov, Valerii Bashev, Serhii Ryabtsev Oles Honchar Dnipro National University, Ukraine High-entropy alloys (HEAs) are a new class of metallic materials that have attracted a lot of attention in recent years. Unlike conventional alloys, which are based on one or two dominant elements with minor additions of other elements, HEAs consist of five or more elements in equal or near-equal proportions. This leads to a high configurational entropy of mixing, which can stabilize simple solid solution phases. HEAs have shown excellent strength, ductility, fracture toughness, wear resistance, corrosion resistance and high temperature stability.
Previous research indicates that Al greatly increases the hardness of CoCrCuFeNi base high entropy alloy. This study investigates how the cooling rate influences the structure, phase formation, and microhardness (Hµ) of Al₄CoCrCuFeNi HEA. The films of the investigated HEA were produced by applying the liquid quenching (LQ) technique to the melt that was obtained from remelting the as-cast ingot. The LQ technique involved the rapid cooling of melt drops upon their impact with the internal heat-conducted surface of a fast rotating (~8000 RPM) hollow cylinder. The cooling rate was estimated to be ~1000000 K/s.
An analysis of the X-ray diffraction patterns made it possible to determine that the structure of the as-cast HEA consisted of a B2 phase that had a lattice parameter a=0.2919 nm. When the liquid quenching was performed, the phase composition remained unchanged, while the lattice parameter became a=0.2916 nm. The microhardness of the as-cast HEA was measured to be Hµ=6500 MPa, while the microhardness of the LQ HEA was significantly higher and reached Hµ=9400 MPa. The reason for this difference in microhardness apparently consists in the fact that the LQ Al4CoCrCuFeNi HEA films were far from the equilibrium state and had a microstructure that was characterized by a higher level of microdeformations, dislocation density, and smaller grain sizes, in contrast to the as-cast samples, which were in a more equilibrium state.
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Oleksandr Kushnerov |
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H3-VK1423 |
Wetting of metal substrates with liquid halides Vitalyi Krasovskyy, Nataliia Krasovskaya Frantsevitch Institute for Problems of Materials Science of NASU, Kyiv, Ukraine Many functional metal materials (brazing alloys, amorphous, shape memory alloys) contain chemical active Zr and Ti. The refractory crucibles used for melting such melts do not ensure the complete homogenization of the alloys. The revealed anomalous phenomenon of non-wetting of alkaline earth metal fluorides by melts at high temperatures [1–4], which contain Ti, Zr, solves the specific problem of obtaining inert refractory materials in contact with chemically aggressive melts. The aim of this work is to study the contact interaction in solid metal/liquid halide systems. Wetting of solid Ti, Ni, Cu, Al substrates by liquid LiF, NaF and MgF2 was carried out by the sessile drop method in a vacuum of 1×10 -3 Pa at the melting temperatures of halides. The surface profile of the substrates after interaction with the halide was studied using the optical method on a non-contact interference 3D profilograph. Liquid LiF, NaF, MgF2 wet Ti, Ni, Cu, Al, contact angles are much less than 90 град., adhesion of melts to substrates is high. At the experimental temperature, liquid LiF, NaF and MgF 2 rapidly evaporate. The losses of the Ti-substrate after wetting with fluorides are much greater than the losses of the Ti substrate after annealing at a temperature of 1553 K. The "hole" is formed under a drop of MgF2 . The roughness of the Ti substrate after annealing is 1–4 μm, and the depth of the “hole” is greater than 14 μm. The study of the geometry of the contact boundary in the solid titanium–liquid LiF, NaF, and MgF2 system confirmed the possibility of the formation of gaseous products of the interaction of Ti with F. Ti-fluorides are characterized by high vapor pressure. The appearance of such compounds ensures that alkaline earth metal fluorides are not wetted by Ti-containing melts at high temperatures exceeding 1400 K. This allows the use of fluorides crucibles as refractories for high-temperature melting, long-term homogenization and casting of alloys with a high content of Ti, Zr [1–4].
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Vitalyi Krasovskyy |
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H3-VT1032 |
Characteristics of hafnium after thermochemical treatment: influence of the surface layer state Vasyl Trush, Iryna Pohrelyuk, Alexander Luk’yanenko, Viktor Fedirko, Taras Kravchyshyn, Serhii Lavrys Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine Hafnium is used for production control rods and protective screens in nuclear reactors after its hot plastic deformation and final thermochemical treatment. This research presents the experimental results of the influence of the surface layer state on the oxygen diffusion saturation of hafnium during thermochemical treatment in an oxygen-containing gas medium. Two cases of the surface layer state were considered: in the initial (delivery) state and after grinding, where 50 µm of the surface layer was removed.
In this research, the differences in the distribution of hardness in the near-surface layer and fatigue life of the hafnium after thermochemical treatment in an oxygen-containing gas medium with the removed defective near-surface layer (after grinding) and not removed were shown.
It was found that for hafnium without removal of the surface layer after hot plastic deformation as a result of thermochemical treatment in an oxygen-containing gaseous medium (850°C for 2 h) in the near-surface layer, the hardness increases from the surface to a depth of 5...7 µm, and then decreases to the matrix stiffness values. Therefore, after the hot plastic deformation of hafnium, a defective «technological» layer of hafnium should be removed from the surface due to its chemical and structural heterogeneity, which can lead to premature failure of the product.
It was shown that thermochemical treatment in an oxygen-containing medium increased fatigue life compared to thermochemical treatment in a vacuum for hafnium without removal and with a removed surface layer. However, the thermochemical treatment in the oxygen-containing medium after grinding of hafnium specimens significantly increased the number of cycles to failure. The fatigue life of samples after thermochemical treatment of an oxygen-containing gas mixture with a removed surface layer is six times greater than the samples without removing the defective layers.
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Iryna Pohrelyuk |
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H3-YN1656 |
Nanocrystallization behaviour of amorphous Co67Fe4Cr7Si8B14 alloy Yulia Nykyruy, Stepan Mudry, Yuriy Kulyk Ivan Franko National University of Lviv, Ukraine Amorphous metal alloys (AMA), also cold as glassy metals or metal glasses, are materials with disordered structure. For a long time they are in focus of researchers due to their unique mechanic, magnetic, electric and other properties. The properties of amorphous materials are related to a disordered structure and sensitive to structure transformation [1, 2]. Amorphous state is metastable one and under external influence, the evolution of the structure occurs, leading to drastic properties changes [3]. Therefore, investigation of structure evolution in these materials is an important research subject.
Our present research is focused on the crystallization behaviour of amorphous Co67Fe4Cr7Si8B14 alloy. This Co-based alloy was obtained by the melt-quenching method in the form of the ribbon 25 µm thick and 1 cm width. Structure transformations were studied by differential thermal analysis (DTA) using synchronous thermal analyzer Linseis STA PT 1600; back-scattered X-ray diffraction method (XRD) with X-ray structure analysis; field-emission scanning electron microscopy (FESEM), and vibrating magnetometer. The temperatures of the onset of the nanocrystallization, phase compositions, grain size and further structure transformations were defined.
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Yulia Nykyruy |
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H3-OS2211 |
Fractal analysis of the structure with non-metallic inclusions characteristics impact on the weld metal mechanical properties Viktor Holovko1, Olha Shtofel1,2, Iryna Krasikova3, Igor Krasikov3 1E. O. Paton Electric Welding Institute NASU, Ukraine The problem of improvement of welds metal structures and mechanical properties remain highly relevant due to the constant increase of high-strength low-alloy steels use in welded constructions. As is well known, the welds metalmechanical properties are determined by their microstructural components, including non-metallic inclusions. Existing analyzing methods of the influence of non-metallic inclusions do not provide sufficient information to describe such important parameters as the inclusions distribution by size and the nature of the inclusion distribution in the metallic matrix. The existing knowledge is based on the non-metallic inclusions peculiarities impact on the steel welds metal mechanical properties and requires constant expansion and deepening, which is the focus of this work.
To form different compositions and sizes of inclusions in the welds metal, high-melting point admixtures were added to the welding pool. The additives chosen were based on titanium compounds, including titanium oxide, titanium carbide, titanium nitride, as well as zirconium and magnesiumoxides.
The research was carried out for investigation thewelds metal structure fractal parameters influence on metal mechanical properties using computerized programs for welds metal structure fractal parameterization. It has been shown that in presence of acting stresses the non-metallic inclusions fractal dimension and the branching boundaries length fractal dimension are an efficient quantitative characteristic of the material structure self-organization process for individual samples.
The fractal dimension depends on the initial structure of the material and modifying effect of inoculants. It can be used in the development of new combinations of materials + inoculants. The data obtained allowed us to conclude that it is possible to predict the mechanical properties of the weld metal using fractal parameters of the structure and non-metallic inclusions.
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Olha Shtofel |
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H3-YS1552 |
Low-temperature physical and mechanical properties of doped non-equiatomic high entropy alloys of the Fe-Co-Ni-Cr system Yuri Semerenko, Viktor Zoryansky B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine High-entropy alloys (HEAs) were first manufactured in 2004 [1]. Initially, it was believed that such materials should consist of at least 5 elements, the concentration of which is close to equiatomic. At the same time, the structure of such HEAs will consist of simple single-phase solid substitution solutions with fcc or bcc lattices. It was also established that the strength of such equiatomic HEAs, by analogy with traditional alloys, can be further improved by reducing the size of grains in their structure to the nanoscale. However, the increase in strength of equiatomic HEAs with a decrease in grain size was accompanied by a harmful decrease in their plasticity and impact strength.
Efforts to overcome this obstacle have led to the appearance in the last few years of non-equilibrium multiphase non-equiatomic HEAs. In contrast to balanced single-phase HEAs, these materials were created on the basis of multicomponent solid substitution solutions with concentration of components different from the equiatomic. Thanks to activate alternative mechanisms of plasticity during preliminary deformation, it is possible to increase the plasticity of these HEAs while maintaining high strength. Such alternative mechanisms of plasticity are "plasticity induced by twinning" - TWIP and/or "plasticity induced by phase transformations" - TRIP.
It is hoped that further enhancement of the plasticity of such alloys is possible by adjusting the contribution of competing TWIP and TRIP mechanisms through doping [2, 3].
In this work, for the first time, the elastic and dissipative properties of doped non-equiatomic high entropy alloys of the Fe-Co-Ni-Cr system were measured and analyzed by the method of resonant mechanical spectroscopy. In a wide temperature range of 4.2–425 K, a correlation was established between the features of the temperature dependences of the dynamic Young's modulus and internal friction with changes in the phase and structural state.
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Yuri Semerenko |
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H3-YN1003 |
Features of the structural formation of tungsten single crystals in the shape of hollow rotational bodies Yuriy Nikitenko, Viktor Shapovalov, Volodymyr Yakusha, Oleksandr Gnizdylo, Olena Berdnikova Е.О. Paton Electric Welding Institute of the NAS of Ukraine Today, there is a need for single crystals of refractory compounds for the production of powerful solid-state lasers and ultrasensitive scintillators, as well as for the production of ultraviolet LEDs, which requires the production of highly active semiconductors grown using crucibles. There are certain requirements for these crucibles, such as minimal contamination of the melt, high operating temperatures (>1800°C), and a minimal CLTE, among others. Taking into account this set of properties, tungsten single crystals most fully meet these requirements.
Solving the issue of increasing the stability of tungsten crucibles is related to creating a defect-free, dense, and uniform structure.
According to the unique technology of growing single crystals of tungsten developed at the E.O. Paton EWI, an ingot in the form of a hollow body of rotation was made (Ø 85 mm, wall height 68 mm, and wall thickness 20-22 mm). This technology of growing is based on the layer-by-layer formation of the cylinder wall on a single crystal seed crystal.
The study of microhardness showed an average value of 4150 MPa for the vertical plane and 3840 MPa for the horizontal plane. A pronounced difference in microhardness in different planes indicates the anisotropy of properties inherent in a single-crystal structure. Conducting metallographic studies showed the homogeneity of the structure, the absence of defects between the deposited layers, and no grain boundaries were detected. The structure had clear subboundaries without dislocation density gradients. The distribution of dislocations in the volume of the single crystal was uniform, with a density of (4–6) 10*7 cm*-2. Subboundaries also had inhomogeneities in the form of dislocation plexuses when the density of dislocations increased. The calculation of misorientation angles based on diffraction patterns from substructure elements showed that was less than 2°, which did not exceed the permissible norm of 3°.
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Yuriy Nikitenko |
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H3-OS1449 |
Investigation of crystallization processes of Co68Fe4Cr4Si13B11 amorphous alloy by in-situ high temperature XRD method. Oleksanr Smolyakov1, Michal Strach2, Tetiana Dmitrenko2 1Zaporizhzhia National University, Ukraine There are a number of works [1-3] on the Co68Fe4Cr4Si13B11 amorphous metal alloys (AMA) crystallization study. The results presented in these works are contradictory in nature with respect to the phases that form during heating or annealing of this alloy. For example, it was indicated in [2] that crystallization under isothermal annealing conditions leads to the formation of solid solutions based on cobalt and Co3B boride. In [3], Co3B boride was not detected, but the formation of additional Co21Cr2B6, Co2B and Co2Si phases was indicated. Therefore, the aim of this work was a detailed study of the crystallization processes of AMA Co68Fe4Cr4Si13B11 during continuous heating at a rate of 6 K/min and after isothermal annealings. A study was carried XRD in-sity on a D8 Advance (Cu-K) diffractometer in the angle range from 40° to 50° in the temperature range from 303 to 1043 К.
It has been established that, upon continuous heating, the crystallization of the alloy began at a temperature of 773 K with the formation of hcp and fcc cobalt. Subsequently, at a temperature of 803 K, the samples completely crystallized with the appearance of additional diffraction peaks. At a temperature of about 923 K, these peaks disappeared with the appearance of new diffraction peaks. At a temperature of 1043 K, another similar phase transformation took place. To determine the phase composition of the samples in different heating temperature ranges, precision XRD studies of the samples after annealing at 823, 973, and 1073 K were carried out. An analysis of the results showed that, above a temperature of 1043 K, the alloy included phases based on hcp and fcc cobalt and Co2B. In the temperature range from 923 to 1043 K, the Co21Cr2B6 and Co2Si phases were additionally fixed. In the temperature range of 803–923 K, the alloy composition included phases based on hcp and fcc cobalt, Co3B, and one or two unknown phases.
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Oleksanr Smolyakov |
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H3-KS2213 |
Effect of the stress-strain state on the properties and structure formation of materials of the Fe-Al system under hot deformation Stepan Kyryliuk, Oleksandr Tolochyn, Oleksandra Tolochyna, Genadii Bagliuk Franctsevich Institute for Problems of Materials Science NAS Ukraine One of the directions for the creation of new materials at today's stage of scientific and technical progress is to obtain alloys and composites with predetermined properties. Fe3Al-based iron aluminides are considered as substitutes for stainless steels due to better resistance to corrosion, sulphidation, oxidation and a better strength-to-weight ratio. The study of the effect of the deformation scheme on the processes of structure formation and physical and mechanical properties is an urgent task for obtaining materials with specified properties.
To determine the evolution of the stress-strain state and densification in the process of hot deformation of materials of the Fe–Al system, a computer simulation of the hot forging process was carried out using the Deform 2D/3D software. The previously synthesized Iron aluminide Fe-28Al-5Ti (at.%) was subjected to deformation processing in a semi-closed die at temperatures of 800 and 1100°C. After hot deformation, the mechanical properties and microstructure of the samples were studied.
The simulation results show that residual porosity of the sample for a temperature of 800°C is uneven in volume (0–8.3%). At a temperature of 1100°C, the distribution of residual porosity is more uniform (0.6–0.7%).The experimental porosity of the sample deformed at temperatures of 800 and 1100°C is 3.8 and 0.9%, respectively. Analysis epures of the distribution of the total velocity vector and strain components showed at the initial stages, the axial strain component prevails, but after filling the matrix cavity, the radial strain component comes to the forefront. At the final stages of the process, the accumulation of deformations occurs due to the movement of material into the pore volumes during the compaction process. After hot deformation, the resulting structures are characterized by elongated grains and flat porosity. The bending strength of the samples obtained after deformation at 800 and 1100°C is 360 and 985 MPa, respectively.
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Stepan Kyryliuk |
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H3-SL0552 |
Feature of microstructural evolution and corrosion behavior Ti6Al4V alloy obtained from elemental powder blends Serhii Lavrys1, Iryna Pohrelyuk1, Dmytro Savvakin2, Khrystyna Shliakhetka3, Mariia-Olena Danyliak1 1Karpenko Physico-Mechanical Institute of the NAS of Ukraine Sintered Ti–6Al–4V alloys prepared from TiH2/60Al40V powder blends under various technological conditions were studied. The microstructural evolution was investigated by X-ray diffraction, scanning electron microscopy, optical microscopy, and energy dispersive X-Ray analysis. The corrosion resistance of sintered titanium alloy was evaluated by the static immersion test according to ASTM standard G31-72(2004) in 40 wt.% H2SO4 solutions. Depending on powder metallurgy processing parameters (powder size, compaction pressure, sintering temperature), the Ti6Al4V alloy was obtained with various structural features (porosity, chemical, and structural heterogeneity). It was shown that those structural features of sintered Ti6Al4V alloy are a key microstructural factor that determines their corrosion resistance. For instance, an increase in porosity leads to enhanced corrosion resistance. Based on the current research, the optimal parameters of powder metallurgy manufacturing of Ti6Al4V alloy, ensure the achievement of characteristics sufficient for practical use in aggressive conditions of the chemical industry.
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Serhii Lavrys |
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H3-ST6593 |
Microstructure and densification mechanism of Al-15Fe alloy prepared by metallurgy route Serhii Teslia, Anatoliy Stepanchuk, Mariia Kruzhkova, Daria Chyzhska, Danylo Sudakov Igor Sikorsky Kyiv Polytechnic Institute, Ukraine Aluminum-based alloys, due to their relatively high specific strength, low density, and high corrosion resistance, are the main materials for the production of multifunctional parts. Dispersion-strengthened aluminum alloys have a limited range of use due to the loss of properties at elevated temperatures.It is possible to increase high-temperature properties when using alloying elements with low solubility in aluminum, like iron. In this work, the conditions for obtaining Al-15Fe powder alloys by methods of pressing and sintering at different holding time were studied. The initial powders were obtained by centrifugal atomization, based on the prediction that due to the high cooling rate in this case (more than 10-5 K/s), the intermetallic phase will be in a dispersed state. The microstructural and XRD showed that their structure consists of a matrix phase with α-Al and inclusions of the metastable phase Al6Fe and the stable phase Al13Fe4. The paper studied the effect of powder particle size (100, 200, 282, 357 μm) and pressing pressure (300-800 MPa) on the process of their compaction using the static pressing method. The relative density of pressings increases monotonically with increasing pressing pressure from 300 to 800 MPa, from 75% to 96%, which is typical for the compaction of plastic materials. The size of the particles practically does not affect the degree of compaction.The process of sintering of the obtained samples at a temperature of 500 °C and a holding time of 30 min was studied. For all cases, there is a negative shrinkage, which decreases with increasing pressing pressure. The latter can be caused by the action of two competing processes - the pressure of crystallization and the action of sintering mechanisms, which contribute to shrinkage. During heating, a crystallographic transformation of metastable to stable Al13Fe4 phase occurs, which is accompanied by an increase in specific volume, which is the cause of negative shrinkage.
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Serhii Teslia |
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H3-AS1458 |
Phase equilibria of the Hf–Ni–Ti system at solidus temperatures Anastasiia Storchak, Maryna Bulanova, Tichonova Iryna, Samelyuk Anatoliy Frantsevich Institute for Problems of Materials Science NAS of Ukraine Hf-Ni-Ti alloys are of interest as amorphous materials. To control their properties, information on phase equilibria in the region of crystallization is necessary. The Hf-HfNi-TiNi-Ti subsystem was studied in detail in [1, 2] . Additionally, isothermal sections at 800 °С and 900 °С were plotted in [3]. The section HfNi-TiNi turned out to be quasibinary. No information is available concerning phase transformations in the crystallization interval in the subsystem HfNi-Ni-TiNi. The aim of the present study is to plot the solidus projection of this subsystem.
The alloys were melted in an arc furnace in Ar from iodide Hf and Ti and electrolytic Ni. The alloys were annealed for 30 h at subsolidus temperatures (by 20–40 °С lower than incipient melting temperatures of the as-cast alloys determined by DTA). Annealed and as-cast alloys were studied by differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD).
The projection of the solidus surface of the subsystem of interest is characterized by presence of 10 three-phase and 20 corresponding two-phase regions.
The main feature of the solidus projection is the presence of a new ternary compound (τ) of approximate composition 15Hf-65Ni 20Ti at. %. It melts congruently and has noticeable homogeneity region: from 64-66 at. % Ni and 17-22 at. % Ti. It is in equilibria with the following phases: (Hf,Ti)Ni, TiNi3, and βHfNi3.
The homogeneity regions of all the binary compounds at solidus temperatures widely extend to the ternary. Ti solubility in HfNi3, Hf7Ni10, Hf2Ni7, Hf3Ni7, Hf9Ni11, Hfi5Ni were established as 25.5; 14; 4.5; 4; 2 and 1 (at. %), respectively. TiNi3 has a large solubility region: from 64-66 at. % Ni and 17-22 at. % Ti. The continuous solid solutions (Hf,Ti)Ni dissolves up to ~10 at. % Ni. On the HfNi side the solubility decreases exponentially.
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Anastasiia Storchak |
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H3-AS1510 |
Projection of the liquidus surfase in the Hf–Ni–Ti system in the HfNi–Ni–NiTi region Anastasiia Storchak, Maryna Bulanova, Konstantin Meleshevich, Anatoliy Samelyuk Frantsevich Institute for Problems of Materials Science NAS of Ukraine The Hf-Ni Ti system is of great practical and scientific interest due to existence of wide region of amorphous state of alloys and shape memory alloys. In [1] the liquidus surface of the ternary system was studied in the range of nickel content 0-50 at. %. No experimental data on phase equilibria with participation of the liquid phase are available for the Ni-rich region. The thermodynamic modeling and calculation of the liquidus projection in the Hf-Ni Ti system was done in [2]. However, our results show the necessity of its experimental study.
The aim of the present work is experimental investigation of phase equilibria in the HfNi–Ni–NiTi region of the Hf–Ni–Ti system and construction of the preliminary liquidus surface projection.
The alloys for investigation were melted in an arc furnace in Ar from iodide Ti and Hf and electrolytic Ni. As-cast alloys were studied by differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffraction phase analysis (XRD).
The liquidus projection is characterized by the presence of primary crystallization fields of (Hf, Ti)Ni, (Ni), and all phases based on Hf-Ni and Ti-Ni compounds (nickel content 50-100 at. %), which in binary systems form with the participation of the melt. The largest field is for continuous solid solutions (Hf, Ti)Ni up to 64,5 at. % Ni.
The new congruent ternary compound (τ) of approximate composition 15Hf-65Ni 20Ti at. %, was found in the system. It has the wide primary crystallisation field within 62,5-68,5 at. % Ni and 15-27 at. % Ti.
There are 10 invariant four-phase equilibria with participation of the liquid phase.
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Anastasiia Storchak |
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H3-NR1653 |
Estimation of the Lattice Parameter and Distortion of Atoms Based on the Results of Ab initio Study of Structural Fragments of TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf Multicomponent Equiatomic Alloys Nataliia Rozhenko, Liubov Ovsiannikova, Valery Kartuzov Frantsevich Institute of Materials Science Problems, National Academy of Sciences of Ukraine An approach is proposed for determining the lattice parameters and the degree of atomic distortion in multicomponent bcc alloys based on the results of an ab initio study of isolated atomic clusters – fragments of their structure. Isolated clusters - fragments of the bcc structure consisting of 15 and 65 atoms - were built. Three 15-atomic Ti3V3Zr3Nb3Mo3 equiatomic clusters have different disordered mutual arrangement of atoms. In the 65-atom Ti13V12Zr14Nb14Mo12, Ti13V12Zr14Nb14Ta12, and Ti13V12Zr14Nb14Hf12 clusters, the elements are arranged according to coordination spheres. The constructed clusters were studied in the framework of DFT methods using the Gaussian complex with the B3LYP hybrid functional and the STO-3G basis set and GAMESS with the PBE0 functional and the MINI basis set. The lattice parameter, determined from the optimized cluster geometry, was extended to the solid structure using a correction factor. The value of the lattice parameter of the equiatomic TiVZrNbMo alloy established from 15-atom clusters is 0.3231±0.0002 (nm) and coincides with the experimental value for the corresponding coating of 0.3230 nm [1]. The lattice parameters of the TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf equiatomic coatings, calculated from 65-atom clusters, are 0.3222, 0.3280, and 0.3327 (nm), respectively, in agreement with the experimental values (0.3230, 0.3264, 0.3336 (nm), [1]). The root-mean-square deviation of the lengths of the radius vectors of the positions of atoms in a cluster from the radius of the corresponding coordination sphere of an ideal lattice was taken as a quantitative measure of distortions in the lattice. The calculated distortions are 0.011, 0.015, and 0.020 (nm) for the TiVZrNbMo, TiVZrNbTa, and TiVZrNbHf equiatomic coatings, respectively. The approach can be recommended for predicting the lattice parameter and distortion of new prognosticated multicomponent alloys.
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Nataliia Rozhenko |
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H3-KS2339 |
Development Status and Disadvantages of Well-Known TDA Methods for the Chemical Composition and Properties of Cast Iron Kateryna Sirenko, Valeriy Mazur Physical and Technological Institute of Metals and Alloys of the National Academy of Sciences of Ukraine The quality of castings depends on the processes that occur during the liquid iron stage, with optimal temperature conditions and compliance to regulated standards for metal composition. Melting and holding the metal affect furnace wear, volatilization, and energy consumption, increasing production costs. Melting time can be reduced by enhancing prompt quality control and adjusting composition before pouring into molds. Existing rapid analysis methods are limited to chemical analysis, except for thermal methods like Thermal Derivative Analysis (TDA).
TDA identifies critical temperatures on the cooling curve of liquid cast iron, dependent on structural components. By calculating derivatives, TDA provides reliable results for assessing the composition and structure of cast iron. However, implementing this method faces difficulties, necessitating scientific and technological development and improvement.
In TDA, the quality of liquid cast iron is evaluated by comparing its thermal cooling curve (TCC) with a reference cooling curve (RCC) from a database. RCC reflects the influence of microstructural components on the cooling curve, determined by latent heat release during solidification. Predicting the casting structure allows determination of quality indicators and chemical composition. The method's improvement lies in comparing TCC and RCC using a patented recognition criterion called Z (zet). A smaller criterion value indicates similar curve shapes, with a minimum or zero criterion implying the most similar pair and equivalent cast iron properties.
To implement the TDA method effectively, stability of sample volume and temperature, uniform heat dissipation, environmentally friendly sample collectors, and adaptable curve processing methods are crucial. Therefore, considering melted cast iron as an object of rapid thermal control, improving rapid chemical composition control, and exploring new efficient means for multi-elemental composition control are necessary.
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Kateryna Sirenko |
Contacts
Conference Secretary: Storozhenko Maryna
E-mail: conference@umrs.org.ua
E-mail: conference@umrs.org.ua