Термодинамическая устойчивость микрогетерогенных состояний в расплавах Fe – Mn – C

The probability of the existence of microheterogeneous states in Fe - Mn - C melts has been analyzed in accordance with the concepts of chemical thermodynamics. The microheterogeneous state of a chemically heterogeneous Fe - Mn - C melt was understood as the presence of dispersed Fe - C particles in it. These are suspended in the Mn - C medium and separated from it by an interface. The microheterogeneous state in Fe - Mn - C melts is destroyed as a result of heating to a temperature specific for each composition. The hypothesis of the microheterogeneous state of Fe - Mn - C melts is supported by a wide range of numerous experimental data on their thermodynamic and physical properties. The identification of anomalies in temperature dependences of physical properties of Fe - Mn - C melts has allowed for temperature values above which the melt superheating treatment (MST) causes destruction of microheterogeneity to be determined, i.e., liquid - liquid structure transition (LLT) in the melt. LLT is understood by the authors as a structural transition "microheterogeneous melt - homogeneous solution". This is expressed as the destruction of the microheterogeneous state when the Fe - Mn - C melt is heated to a temperature specific for each composition (MST). The authors have previously analyzed the effect of LLT in Fe - Mn - C melts on the microstructure, crystal structure and mechanical properties of solid metal in submicrovolumes. This paper describes a method of theoretical determination of the temperature range where the microheterogeneous state of the Fe - Mn - C melt is thermodynamically stable. The thermodynamic stability of dispersed Fe - C particles in the Mn - C medium has been estimated according to the equations proposed by G. Kaptay for a regular solution. It was assumed that the interface between the dispersed particle (Fe - C) and the dispersion medium (Mn - C) is enriched with carbon. The paper demonstrates the possibility of existence in the Fe - Mn - C melt of dispersed Fe - C particles with sizes from 2 to 34 nm, distributed in the Mn - C dispersion medium and separated from it by an interface with increased carbon content. The estimated result is consistent with the data on the size of structural units of a viscous flow, obtained earlier within the framework of the theory of absolute reaction rates. © 2022 National University of Science and Technology MISIS. All rights reserved

Study of structure-property relationship in polycrystalline steels based on analysis of EBSD data

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used

Surface Tension and Density of Fe–Mn Melts

Abstract: The article presents original experimental data on surface tension of the Fe100 – xMnx (x = 4–13 wt %) melts. Surface tension and density of the melt were measured by the sessile drop method at heating from the liquidus temperature to 1780°C and subsequent sample cooling in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe–Mn melts were plotted. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe–Mn melts decreases as Mn content increases. Experimental data on the surface tension of Fe–Mn melts is consistent with the theoretical dependences (the Pavlov–Popel’ equation and the Shishkovsky equation). During the investigation of Fe–Mn melt microheterogenity, correlation between the values of kinematic viscosity, surface tension, and density is revealed. Fluidity dependence of Fe–Mn melts on their density in the cooling mode has a linear character which indicates satisfaction of the Bachinskii law. Discrepancy in the melt viscosity ratios to the surface tension coefficient obtained from the experimental data and from the empirical formula is discovered. Using the experimental data on viscosity and surface tension of Fe–Mn melts, the entropy change in the melt’s bulk and the change in the melt’s surface entropy, respectively, are studied. The surface entropy and the bulk entropy in the melt decrease in their absolute value with its increasing Mn content. From the study results, it is concluded that there is no destruction of the microheterogeneous structure of Fe100 – xMnx (x = 4–13 wt %) melts when heated up to 1780°C. © 2020, Allerton Press, Inc.The reported study was funded by Russian Foundation for Basic Research, project no. 19-33-90198

Study of structure-property relationship in steels based on analysis of EBSD data

In this work, we formulate novel data-driven assays for exploring the structure-property linkages for high-manganese austenitic wear-resistant steel 110G13L (Hadfield steel). Steel 110G13L has the following chemical composition, wt.%: C(0.95-1.50)-Mn(11.5-15.0). These assays are built on recent advances in high resolution quantification of material structure using correlations and principal analyses of electron backscatter diffraction (EBSD) data, as well as in the mechanical characterization using nanoindentation. These novel protocols are demonstrated on a steel 110G13L that exhibits various polycrystalline microstructures. A comparative analysis of EBSD data was carried out for samples of manganese steel 110G13L obtained by various methods. Analysis of the diffraction patterns of backscattered electrons allowed us to plot orientation maps, Schmid factor maps and distributions for austenite dendrites. Schmid factor maps are used to determine the degree of homogeneity of a possible deformation. The results of the measurement of hardness and Young's modulus for the austenite dendrites indicate the heterogeneity of the mechanical properties of the material in submicro-volumes due to lattice defects (dislocations) inside the crystallites. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 19-33-90198The equipment of the Ural Centre for Shared Use “Modern nanotechnology” UrFU was used. The reported study was funded by RFBR (project No. 19-33-90198)

About possibility to locate an EQ epicenter using parameters of ELF/ULF preseismic emission

A relation between parameters of preseismic ULF/ELF emissions and EQ is studied. The magnetic data measured at Karymshino station (Kamchatka, Russia) along with data on local seismic activity during eight years of observations (2001–2008) are taken for the analysis. Source azimuth is detected in different techniques, based on the analysis of the total field and its polarized pulsed component. The latter technique shows a better accuracy in the source azimuth detection. The errors of the method are associated with existence of non-seismic sources and with use of one-point observation. The second error can be eliminated by development of multi-point observations

MICROHETEROGENICITY OF LIQUID CAST IRON ICH300H30F4N5KB

Experimental data on the electrical resistivity and kinematic viscosity of liquid cast iron ICH300H30F4N5KB are presented. The parameters of microheterogeneity are estimated: the volume fraction and the size of dispersed particles.Статья выполнена в рамках государственной работы № FEUZ-2023-0015

Сосудистые кальцинаты молочной железы как проявление системного атеросклероза

Cardiovascular diseases (CVD) are socially significant diseases and one of the main causes of death among women. There are no effective and uniform screening methods to prevent the prevalence and mortality of CVD. Breast artery calcifications may be one of the available tools for CVD risk stratification. The pathogenesis of calcification of the middle vessel wall, known as Mönckeberg's arteriosclerosis, is different from the pathogenesis of coronary atherosclerosis that coronary arteries. However, research data supports a correlation between breast artery calcifications and risk factors for CVD. These factors include coronary atherosclerosis, detected by CT-coronarography.Purpose. To assess the prevalence of breast arterial calcification and to determine the association with cardiovascular risk factors, coronary artery calcification, atherosclerosis of brachiocephalic arteries and visceral branches of the abdominal aorta.Material and methods. 21 patients were hospitalized in the cardiology department. The patients underwent digital mammography to detect breast arterial calcifications. All patients also underwent CT coronary angiography with angiography of the abdominal aorta.Results. The use of the Wilcoxon-Mann-Whitney W-test with an abnormal distribution showed a correlation between the breast arterial calcifications and the calcium index (p = 0.0028), coronary artery stenosis (p = 0.040), calcification of the thoracic aorta wall (p = 0.035) and stenosis of the visceral branches of the abdominal aorta (p = 0.037).Conclusions. The breast arterial calcifications correlates with a more frequent detection of calcifications in the walls of the coronary arteries and a higher calcium index.Сердечно-сосудистые заболевания (ССЗ) относятся к социально значимым заболеваниям и являются одной из основных причин смертности среди женщин. Отсутствие эффективных и унифицированных методов скрининга препятствует уменьшению заболеваемости и распространенности ССЗ и смертности от них. Сосудистые кальцинаты в молочной железе могут стать одним из доступных инструментов страти фикации риска ССЗ. Патогенез кальциноза средней оболочки артерий, известный как артериокальциноз Менкеберга, отличается от патогенеза атеросклероза интимы, возникающего в коронарных артериях. Тем не менее исследования подтверждают корреляцию между сосудистыми кальцинатами в молочной железе и факторами риска ССЗ. К таким факторам относится атеросклероз коронарных артерий, выявляемый с помощью КТ-коронарографии.Цель работы: изучение связи сосудистых кальцинатов в молочной железе с факторами риска сердечно-сосудистых заболеваний, атеросклерозом коронарных артерий, брахиоцефальных артерий и висцеральных ветвей брюшной аорты.Материал и методы. 21 пациентка, находящаяся на стационарном лечении в отделении кардиологии, была обследована на наличие сосудистых кальцинатов в молочных железах с помощью цифровой маммографии. Также всем пациенткам была выполнена КТ-коронарография с ангиографией брюшной аорты.Результаты. Применение W-критерия Уилкоксона–Манна–Уитни при ненормальном распределении показало взаимосвязь между наличием сосудистых кальцинатов в молочной железе и кальциевым индексом (р = 0,0028), стенозами коронарных артерий (р = 0,040), кальцинозом стенки грудной аорты (р = 0,035) и стенозами висцеральных ветвей брюшной аорты (р = 0,037).Заключение. Наличие кальцинатов в стенках сосудов молочных желез коррелирует с более частым выявлением кальцинатов в стенках коронарных артерий и более высоким кальциевым индексом

Surface tension and density of Fe-Mn melts

The article presents original experimental data on surface tension of the melts Fe100 - xMnx (x = 4... 13 wt. %). Surface tension and density of the melt was measured by the method of sessile drop at heating from the liquidus temperature up to 1780 °C and subsequent cooling of the sample in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe-Mn melts was constructed. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe-Mn melts decreases while Mn content increases. Experimental data on the surface tension of Fe-Mn melts is consistent with the theoretical dependences (Pavlova-Popiel equation and the Shishkovsky equation). During the study of microheterogeneity of Fe-Mn melts, correlation between the values of kinematic viscosity, surface tension and density was determined. Dependence of the fluidity of Fe-Mn melts on their density in the cooling mode has a linear character which indicates the implementation of the Bachinsky law. Discrepancy of values of the ratio of melt viscosity to the surface tension coefficient was obtained from experimental data and was calculated by the empirical formula. According to the experimental data on viscosity and surface tension of Fe-Mn melts, the authors have evaluated the entropy change in volume of the melt and change of surface entropy of the melt, respectively. Surface entropy of the melt and entropy in the melt volume decreases in absolute value with increase of Mn content in it. According to the results of the work, it was concluded that there is no destruction of the micro-heterogeneous structure of Fe100 - xMnx melts (x = 4... 13 wt. %) when heated up to 1780 °С. © 2020 National University of Science and Technology MISIS. All rights reserved

VISCOSITY OF MELT Fe12Mn2C

The temperature dependence of the kinematic viscosity of the Fe12Mn2C melt was measured. The results are discussed in the context of studying microheterogeneity and crystallization conditions of the Fe12Mn2C melt within the framework of the theory of absolute reaction rates.Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 19-33-90198