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1
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In Situ Investigation of Microstructure Evolution during Solidification of Mg10CaxGd (x=5, 10, 20) Alloys

100%
Mendis C., Tolnai D., Stark A., Schell N., Kainer K., Hort N.
Acta Physica Polonica A
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2015
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vol. 128
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issue 4
606-610
EN
Mg-Ca-Gd based alloys are investigated as a potential alloy for degradable biomaterials with some promising results. In this investigation the Mg10CaxGd (x=5, 10, 20) were investigated with synchrotron radiation X-ray diffraction during solidification to follow the phase evolution at two different cooling rates at 5 and 50 K min^{-1}. All three alloys show formation of α -Mg followed by Mg₂Ca phase, while only Mg10Ca20Gd alloy contained Mg₅Gd phase during solidification. During cooling α -Mg was first observed between 628 and 632°C at a cooling rate of 5 K min^{-1} while this decreased to 620-628°C with the increase in cooling rate to 50 K min^{-1}. The change in cooling rate from 5 to 50 K min^{-1} did not change the types of intermetallic phases observed but resulted in suppressing temperatures at which the intermetallic phases were first detected.
2
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Self-Similar Solidification of Binary Alloys

100%
Alexandrov D., Ivanov A., Malygin A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 4
795-799
EN
The self-similar crystallization process of a binary mixture from a cooled boundary is studied on the basis of two models with a planar front and mushy layer. Approximate analytical solutions of the process describing the solidification with a mushy layer are found. The theory under consideration is in good agreement with experiments carried out by Huppert and Worster for ice growing from aqueous salt solutions.
3
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Analytical Solution for a Problem of Directional Solidification in a Ternary System

100%
Alexandrov D., Ivanov A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 4
786-790
EN
This paper is devoted to new analytic results relating to the nonstationary dynamics of directional solidification of ternary solutions with two moving layers of the phase transition lying between solid and liquid phases. Explicit analytical solutions of the problem under consideration are constructed on the basis of laboratory experiments carried out by Aitta, Huppert and Worster.
4
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Mushy Layer Formation during Solidification οf Binary Alloys from a Cooled Wall: the Role of Boundary Conditions

100%
Alexandrova I., Alexandrov D., Aseev D., Bulitcheva S.
Acta Physica Polonica A
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2009
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vol. 115
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issue 4
791-794
EN
Motivated by metallurgical and geophysical applications we present a mathematical model describing the process of unidirectional solidification of binary melts or solutions, which is based on the classical Stefan thermodiffusion theory with a planar front up to a time of mushy layer initiation and on the quasi-equilibrium theory of solidification with a constitutionally supercooled region afterwards. The role of boundary conditions imposed at the cooled wall is studied in terms of heat flux coefficients describing ultimately nonlinear dynamics of the process.
5
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Determination of Feederless Casting Limits by Thermal Analysis in Cast Iron

80%
Erturk S., Kumruoglu L., Ozel A.
Acta Physica Polonica A
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2017
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vol. 131
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issue 3
370-373
EN
In this study the determinations of melt quality was carried out by thermal analysis of ductile iron. The aim of the study was to determine the limits of feederless casting after the determination of inoculation quality in cast iron. Production method of pouring into a sand mold in the entirety and without using feeder systems has been investigated. Forms of the solidification and volume change have been investigated with simulation program as functions of inoculation quality, type of resin in the mold and mold rigidity. Results of the analysis have been compared with the results of experimental iron casting.
6
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Crystallography and Morphology of Chromium Rich Eutectic Carbides in an As-Cast Fe-Cr-C Alloy Crystallized in Non-Equilibrium Conditions

80%
Wieczerzak K., Bała P., Tokarski T., Gajewska M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1007-1009
EN
The crystallography and microstructure of eutectic carbides crystallizing in non-equilibrium conditions in hypoeutectic Fe24Cr0.8C have been studied by light microscopy, scanning electron microscopy, and transmission electron microscopy. The alloy was synthesized in an arc furnace in high purity argon atmosphere and crystallized on water-cooled copper mould. Greater thermal gradient in regions close to water-cooled, copper mould in comparison with top of the ingot gives a formation of eutectic carbides with two morphologies: large polygonal carbides and surrounding them much smaller, plate-like carbides instead of rod-like carbides, observed in top of the ingot. There was no evidence for influence of non-equilibrium crystallization to the formation of types of carbides different than M₂₃C₆.
7
Content available remote

Analysis of Phase Transformations in Inconel 625 Alloy during Annealing

80%
Petrzak P., Kowalski K., Blicharski M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1041-1044
EN
The investigation focused on the characterization of the microstructure and chemical composition changes after annealing. The research was conducted on the Inconel 625 weld overlay deposited on a boiler steel. The annealing was performed for 10 h at temperatures from 600 to 1000°C. The microstructure and chemical composition were examined by scanning electron microscope and transmission electron microscope equipped with an energy dispersive X-ray spectrometer. Weld overlays were produced by an innovative method of cold metal transfer.
8
Content available remote

Numerical Analysis of the Rapid Solidification Process of NiTi Binary Alloy

80%
Ternik P., Zadravec M., Svetec M., Rudolf R.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
43-47
EN
The objective of the present work is to analyse the solidification process of NiTi binary alloy. The physical medium is taken as an incompressible fluid where the heat is transferred by conduction and convection, including the thermal phase change phenomenon. The last one is modelled by the improvement procedure called enthalpy-porosity formulation, where the liquid-solid mushy zone is treated as a porous zone with porosity equal to the liquid fraction. The numerical model is based on the finite volume method in body fitted coordinates with a SIMPLER scheme to couple the pressure and velocity fields. The results are presented for the velocity and temperature field, as well as for the NiTi mass fraction during the solidification process.
9
Content available remote

Investigation of Al/Steel Bimetal Composite Fabrication by Vacuum Assisted Solid Mould Investment Casting

80%
Guler K., Kisasoz A., Karaaslan A.
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vol. 126
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issue 6
1327-1330
EN
Bimetal composites are a group of promising engineering materials with high developing and service potential. Especially in many fields they can be a powerful low cost alternative to metal-ceramic composites. The most commonly encountered type of these composites is steel reinforced aluminium matrix composites which stand out with high wear and abrasion resistance. Significant fabrication processes of metal/metal composites are based on liquid metal techniques. In this study, Al/steel composite specimens were produced by using vacuum assisted solid mould investment casting technique. A7075 wrought aluminium alloy were infiltrated into steel preforms, which were produced with 304 stainless steel and H13 hot-work tool steel turnings, in the plaster based solid investment casting moulds. Microstructure observations, HV microhardness measurements, scanning electron microscopy and energy dispersive X-ray spectroscopy analysis were carried out for characterization.
10
Content available remote

Some Applications of the Image Analysis in the Metal Material Science

80%
Odanović Z., Đurđević M., Krstić Pavlović J., Arsić M., Katavić B.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
111-113
EN
In different areas of science such as medicine, biology and engineering the image analysis is widely used. Quantitative measuring by the image analysis has also found application in metal materials science, especially in metallographic microstructure analysis. The measuring of the linear and area dimensions of the microconstituents in the metal material structure performed by the image analysis is presented in the paper. The effects of the heat treatment temperature on the brittle phase content in the structure of the heat resistant Ni-Cr-Co-W alloy were analysed. Investigation of the influence of the alloying elements content in the Al alloys for automotive application, on dendrite arm spacing in the cast structure are also presented. Obtained results of the quantitative measured dimensions have shown direct impact of the process parameters on the analysed metals microstructure characteristics. All tests were performed by the light optical microscope with automatic image analyser. Presented experimental results are based on a large number of measurements. A statistical analysis was performed and a high correlation of the results was obtained. For each of the presented investigations and analyzed phenomenon, a statistical mathematical model is suggested with the boundary conditions defined by the investigated intervals of variables.
11
Content available remote

Anisotropic Phase Field Model of Heteroepitaxial Growth

80%
Hoang D., Beneš M., Stráský J.
Acta Physica Polonica A
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2015
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vol. 128
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issue 4
520-522
EN
We study the heteroepitaxial growth of thin layers by means of the modified phase-field model with the incorporated anisotropy. The influence of elastic and surface energies on the layer growth is considered. For numerical solution of the model, an explicit numerical scheme based on the finite element method is employed. The obtained computational results with various anisotropy settings demonstrate the anisotropic thin-layer pattern growth.
12
Content available remote

Microstructure and Magnetic Properties of La-Ca-Sr-Mn-O Perovskite Ceramics

70%
Zmorayova K., Antal V., Radusovska M., Piovarci S., Kováč J., Kavecansky V., Diko P.
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vol. 126
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issue 1
168-169
EN
La_{0.67}Ca_{0.33-x}Sr_{x}MnO_{3} (x=0.33; 0.03; 0) (LCSM) perovskite magnetocaloric ceramics were prepared by solid state synthesis in air and sintering at 1520°. The phase composition was checked by x-ray powder diffraction. Microstructure analyses were done by scanning electron microscopy. The influence of high pressure oxygenation on magnetisation behaviour is shown.
13
Content available remote

Fabricating of Steel/Cast Iron Composite by Casting Route

70%
Ertürk S., Çakır O., Kumruoglu L., Ozel A.
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vol. 125
|
issue 2
452-453
EN
In this study, 1.2333 cold work tool steel and cast iron (GG 25) were simultaneously melted in different furnaces to fabricate composite die mold used in sheet metal forming industry. To enhance the metallurgical bond between two components of composite part, the pouring temperature of cast iron was assessed just above the solidus temperature, then metallurgically prepared cast iron was poured on to the cast tool steel. The temperature and casting parameters were monitored and simulated. Experimental and simulation results were compared, finally the optimum parameters and casting route were revealed.
14
Content available remote

Microstructure and Properties of Y-123/Y-211 Bulk Superconductors with BaCeO_{3} and BaO_{2} Addition

61%
Zmorayova K., Antal V., Radusovska M., Piovarci S., Volochova D., Diko P.
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vol. 126
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issue 1
366-367
EN
YBa_{2}Cu_{3}O_{7-δ} (YBCO) bulk single-grain superconductors were prepared by a TSMG process. CeO_{2}, BaCeO_{3} and BaO_{2} powders were added to nominal composition Y_{1.5}Ba_{2}Cu_{3}O_{7} with the aim to refine Y_{2}BaCuO_{5} (Y-211) secondary particles. Added powders were refined by milling in a friction milling and characterized by X-ray powder difractometry. Thermal properties of the systems were characterized by DTA. Microstructure of samples was studied by PLM. Successful refinement of Y-211 particles size was confirmed by IP measurements. Transition temperatures and field dependences of the magnetic moment for further determination of the critical current densities were obtained using a VSM.
15
Content available remote

Growth Rate of YBa_2Cu_3O_7 Bulk Crystals in Y_{1.5}Ba_2Cu_3 System with CeO_2 Addition

61%
Zmorayová K., Šefčiková M., Volochová D., Kalmanová M., Piovarči S., Diko P.
Acta Physica Polonica A
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2012
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vol. 122
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issue 4
725-727
EN
The growth rate of Y_1Ba_2Cu_3O_{x} bulk single grain (in fact single crystal) superconductors in the system with composition Y_{1.5}Ba_2Cu_3O_{x} and CeO_2 addition was studied in the temperature range 991-1001°C. It is shown that the growth rate of bulk crystal is different for a- and c-growth direction. Slower measured growth rate in studied system than in pure Y_1Ba_2Cu_3O_{x} is related to the composition shift to the three-phase field containing CuO.
16
Content available remote

Influence of Spark Plasma Sintering on Microstructure and Properties of Bulk LaCaSrMnO Magnetocaloric Materials

61%
Zmorayová K., Antal V., Kováč J., Diko P., Noudem J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
804-806
EN
Polycrystalline La_{0.67}Ca_{0.33-x}Sr_xMnO₃ (x=0.33, 0.03, 0) (LCSM) perovskite samples treated by spark plasma sintering technique were investigated. This study proved influence of the sintering temperature on microstructure of these perovskite ceramics. The thermogravimetric measurements revealed the possibility of increase of oxygen content in studied LCSM samples by additional annealing under oxygen atmosphere and low temperature. Finally, the effect of this annealing on magnetic properties was demonstrated.
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