scholarly journals Liquidus Surface and Spinodal of Fe-B-C Alloys

2020 ◽  
Keyword(s):  
Carbon Content ◽  
Boron Content ◽  
Liquidus Surface ◽  
Thermal Analyses ◽  
Primary Phase ◽  
Binary Section ◽  
Quasi Binary Section ◽  
Point Of Intersection ◽  
First Time ◽  
Primary Crystals

In this work the study is performed for the specimens of Fe-B-C alloys with boron content of 0.005–7.0 wt. % and carbon content of 0.4–6.67 wt. %, the rest is iron. According to the findings of microstructure analysis, XRD and differential thermal analyses, the primary phases and the temperatures of their formation are determined. Depending on boron content (in the range of 1.5–8.80 wt. %) and carbon content (0.5–6.67 wt. %) in the Fe-B-C alloys, the primary phases in the process of crystallization are γ-Fe, boron cementite Fe3(CB) and boride Fe2В. The outcomes of the experiment carried out in this work determine the phase composition and phase transformations occurring in the alloys and the liquidus surface is constructed. The findings show that the liquidus temperature for Fe-B-C system alloys is low compared to binary Fe-B and Fe-C alloys. At the liquidus surface of the Fe-B-C alloys, there is a point at boron content of 2.9 wt. % and carbon content of 1.3 wt. % with the lowest temperature of 1375 K and it is the point of intersection of monovariant eutectics. This fact is in a good agreement with the results of other authors. The microstructure of alloys located at the curves of monovariant eutectics is represented by the γ–Fe+Fe2B and γ–Fe+Fe3(CB) eutectics and the primary crystals of Fe2B iron boride in the shell of Fe3(BC) boron cementite. In this paper it is shown experimentally the existence of a quasi-binary section and the coordinates of the peritectic point are fixed: the boron content is 5.0 wt. %, carbon content is 3.0 wt. % and the temperature is 1515 K. The free energy of the Fe-B-C melt is calculated for the first time by the quasi-chemical method and the surface of thermodynamic stability of the Fe-B-C melt is plotted, depending on temperature and boron and carbon content in the alloy. The results obtained in the paper show that in order to obtain a homogeneous Fe-B-C melt, which does not contain any microheterogeneous structure in the form of short-order microregions, it is necessary to perform the overheating more than to 180 K for the region where the primary phase is iron, and no less than to 200 K for the regions with boron cementite and boride.

scholarly journals Structural State and Thermodynamic Stability of Fe-B-C Alloys

2019 ◽  
Vol 20 (4) ◽  
pp. 437-444 ◽  
Author(s):  
N.Yu. Filonenko ◽  
A. N. Galdina ◽  
А.I. Babachenko ◽  
G.A. Kononenko
Keyword(s):  
Phase Composition ◽  
Carbon Content ◽  
Thermodynamic Stability ◽  
Short Range ◽  
Thermodynamic Potential ◽  
Boron Content ◽  
Liquidus Surface ◽  
Temperature Expansion ◽  
High Temperature Expansion ◽  
First Time

The studies were performed for the specimens of Fe-B-C alloys with boron content of 0.005–7.0 wt.% and carbon content of 0.4–5.5 wt.%, the rest was iron. As a result of the experiment carried out in this work, the phase composition and phase transformations occurring in the alloys are investigated and the liquidus surface is constructed; it is shown that the point with minimum temperature of 1375 K at the liquidus surface is observed at boron content of 2.9 wt.% and carbon content of 1.3 wt. %. For the first time, considering the contribution of the first degree approximation of high-temperature expansion of thermodynamic potential into the Gibbs energy of Fe-B-C melt, we obtain the surface of thermodynamic stability of Fe-B-C melt, depending on temperature and content of boron and carbon in the alloy. The findings show that in order to obtain the homogeneous Fe-B-C melt, which does not contain micro-inhomogeneous structures in the form of short-range microregions, it is necessary to perform overheating more than to 150 K.

scholarly journals Phase relations in the CuI-SbSI-SbI3 composition range of the Cu–Sb–S–I quaternary system

2021 ◽  
Vol 23 (2) ◽  
pp. 236-244
Author(s):  
Parvin R. Mammadli ◽  
Vagif A. Gasymov ◽  
Ganira B. Dashdiyeva ◽  
Dunya M. Babanly
Keyword(s):  
Quaternary System ◽  
Composition Range ◽  
Liquidus Surface ◽  
Polymorphic Transitions ◽  
X Ray ◽  
Immiscibility Region ◽  
Binary Section ◽  
Quasi Binary Section ◽  
Polythermal Sections ◽  
Primary Crystallisation

The phase equilibria in the Cu-Sb-S-I quaternary system were studied by differential thermal analysis and X-ray phase analysis methods in the CuI-SbSI-SbI3 concentration intervals. The boundary quasi-binary section CuI-SbSI, 2 internal polythermal sections of the phase diagram, as well as, the projection of the liquidus surface were constructed. Primary crystallisation areas of phases, types, and coordinates of non- and monovariant equilibria were determined. Limited areas of solid solutions based on the SbSI (b-phase) and high-temperature modifications of the CuI (α1- and α2- phases) were revealed in the system. The formation of the α1 and α2 phases is accompanied by a decrease in the temperatures of the polymorphic transitions of CuI and the establishment of metatectic (3750C) and eutectoid (2800C) reactions. It was also shown, that the system is characterised by the presence of a wide immiscibility region that covers a significant part of theliquidus surface of the CuI and SbSI based phases 

scholarly journals The peculiarities of formation and thermodynamic functions of τ-phase

2018 ◽  
Vol 26 (2) ◽  
pp. 37-44
Author(s):  
N. Yu. Filonenko ◽  
O. M. Galdina
Keyword(s):  
Boron Carbide ◽  
Carbon Content ◽  
Thermodynamic Functions ◽  
Thermodynamic Potential ◽  
Boron Content ◽  
Point Of View ◽  
No Formation ◽  
High Temperature Expansion ◽  
Temperature Dependences ◽  
First Time

It is shown that for alloys with boron content of 0.1–6.5% (wt.) and carbon content of 0.3–4.0% (wt.) without pretreatment no formation of cubic boron carbide takes place under crystallization. The cubic boron carbide can be obtained by pre-annealing at a temperature of 1173 K for an hour and further heating to a temperature of 30 K above the liquidus and cooling of alloys with boron content of 2.5–4.0% (wt.) and carbon content of 0.8–3.0% (wt.). Formation of crystals of cubic boron carbide is possible as a constituent of multiphase inclusions for alloys with boron content of 0.1–0.3% (wt.) and carbon content up to 0.4–0.5% (wt). It should be noted that for alloys with boron content of 4.2–6.0% (wt.) and  carbon content of more than 3.0% (wt.) the pretreatment does not result in formation of cubic boron carbide. The increase in boron content in the alloy to 0.3–0.5% (wt.) and carbon content to 0.5–0.7% (wt.) leads to formation of the eutectic α-Fe+Fe23(CB)6, which is arranged on the boundaries of pearlite grains. The thermodynamic functions of Fe23(CB)6 cubic boron carbide are derived for the first time using the Hillert and Staffonsson model and accounting for the first degree approximation of high-temperature expansion of the thermodynamic potential for binary alloys. We obtain temperature dependences of such thermodynamic functions for Fе23(CB)6 phase as Gibbs energy, entropy, enthalpy and heat  capacity CP , as well as calculate their values at the formation temperature of the phase. The approach used in this paper enables to give the most complete from the thermodynamic point of view description of cubic boron carbide formed from a liquid.

scholarly journals Solubility of Boron and Carbon in Ferrite of the Fe-B-C System Alloys

2019 ◽  
Keyword(s):  
Solid Solution ◽  
Carbon Content ◽  
Mass Fraction ◽  
Room Temperature ◽  
Boron Content ◽  
Solubility Limit ◽  
Content Increase ◽  
X Ray ◽  
First Time ◽  
Structure Imperfection

Investigation was carried out for Fe-B-C alloys with carbon content of 0.0001–0.01 % (wt.) and boron content of 0.0001–0.01 % (wt.), the rest is iron. To determine the structural state of alloys we use the microstructure analysis, X-ray microanalysis and X-ray structure analysis. The level of microstraines, dislocation density and the coercive force of ferrite is determined, and it is shown that structure imperfection grows with boron content increase in the alloy. The obtained results enable to suggest that boron atoms in a solid solution of α-iron occupy substitutional-interstitial positions depending on boron content. In the paper it is shown experimentally, that at room temperature solubility limit of boron and carbon in the ferrite is 0.00012 % (wt.) and 0.006 % (wt.). When boron and carbon content increases further, the following phases are formed: Fe2B, Fe3(CB) and Fe23(CB)6. In this paper by means of quasi-chemical method we obtain for the first time temperature dependence of the free energy for α-iron solid solution, as well as solubility limit of carbon and boron. Maximum mass fraction of carbon may be up to 0.016 % (wt.), and maximum boron mass fraction – up to 0.00025 % (wt.). At room temperature the boron solubility limit in ferrite is 0.0001 % (wt.), and carbon one is 0.004 % (wt.). The calculated numerical values of the solubility of boron and carbon in ferrite of the Fe-B-C system alloys are less than that of the experimental results. This can be explained by the fact that boron atoms interact more actively with structure imperfections than carbon atoms. At high temperatures the solubility of carbon and boron in given phase increases.

scholarly journals Влияние дефектности углеродной подрешетки на упругие свойства кубического карбида титана TiC-=SUB=-y-=/SUB=-

2021 ◽  
Vol 63 (11) ◽  
pp. 1921
Author(s):  
А.И. Гусев
Keyword(s):  
Shear Modulus ◽  
Titanium Carbide ◽  
Carbon Content ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Stoichiometric Composition ◽  
Elastic Stiffness ◽  
Crystallographic Direction ◽  
Simultaneous Increase ◽  
First Time

Changes in the elastic constants cij of disordered cubic titanium carbide TiCy with an increasing the defectiveness of the carbon sublattice are estimated for the first time. It was found that the deviation of titanium carbide from the stoichiometric composition TiC1.0 leads to a decrease in the elastic stiffness constants cij of disordered TiCy carbide with a simultaneous increase in elastic anisotropy. The distributions of Young's modulus E and Poisson's ratio μ in the (100) plane and the distributions of the shear modulus G in the (100), (110), and (111) planes have been calculated as functions on the crystallographic direction [hkl] and on the relative carbon content y in TiCy carbide. The lowest values of the shear modulus Ghkl for TiCy are observed in the (111) plane.

scholarly journals Research of tнe quasi-binary section SmGe2 – LuGe2

2018 ◽  
Vol 59 (1) ◽  
pp. 83
Author(s):  
O. Kravchuk ◽  
Z. Shpyrka ◽  
N. German ◽  
V. Pavluk
Keyword(s):  
Binary Section ◽  
Quasi Binary Section

scholarly journals PHASE EQUILIBRIUM IN THE INAS2SE4 -INAS2SSE3 AND PROPERTIES OF THE FORMED PHASES

2021 ◽  
Vol 7 (8(62)) ◽  
pp. 38-42
Author(s):  
RUZGARA SEVIM MAGAMMADRAGIMOVA
Keyword(s):  
Phase Diagram ◽  
Phase Equilibrium ◽  
Solid Solutions ◽  
Room Temperature ◽  
Quaternary System ◽  
Lattice Parameters ◽  
Binary Section ◽  
Quasi Binary Section

The character of the interaction in the InAs2Se4 -InAs2SSe3 system was investigated and its phase diagram was constructed by DTA, XRD, MSA, as well as by measuring the microhardness and determining the density of the alloys. It was found that the InAs2Se4 -InAs2SSe3 section is a quasi-binary section of the In-As-S-Se quaternary system. Solid solutions based on InAs2Se4 at room temperature reach 10 mol % InAs2SSe3, and on the basis of InAs2SSe3 it extends to 15 mol % InAs2Se4. The lattice parameters are calculated from the region of solid solutions based on InAs2Se4 and InAs2SSe3.

scholarly journals Spectroscopic and Thermal Analyses of Ortho-Benzylphenol Crystalline Polymorphism

2018 ◽  
Vol 63 (2) ◽  
pp. 95 ◽  
Author(s):  
J. Baran ◽  
N. A. Davydova ◽  
M. Drozd ◽  
E. A. Ponezha ◽  
V. Ya. Reznichenko
Keyword(s):  
Structural Changes ◽  
Metastable Phase ◽  
Thermal Analyses ◽  
Aromatic Rings ◽  
Methylene Bridge ◽  
Glass Forming ◽  
The Difference ◽  
Crystalline Polymorphism ◽  
First Time

In situ, we present the experimental spectroscopic proof of the existence of polymorphism in ortho-benzylphenol. Infrared spectroscopy was used for the first time to investigate the structural changes during the crystallization of a metastable phase, which is transformed, in the course of time, into a stable one. The results show that, in the stable and metastable phases, different conformers of ortho-benzylphenol molecule predominate, which differ in the orientation of the aromatic rings relative to the connecting methylene bridge. Namely, it is shown that the transformation of the metastable phase into a stable one is accompanied by the rotation of the OH-substituted aromatic ring relative to the connecting methylene bridge from 59.9∘ to 180.0∘ in the molecule of ortho-benzylphenol. The DSC experiment has shown that the process of nucleation of a metastable phase preferentially develops below ∼1.1 Tg (243 K), the crystallization occurs at ∼272 K, and the melting happens at 290.2 K. The difference in the temperature regions of nucleation and crystallization explains a good glass-forming status of ortho-benzylphenol.

Quasi-Binary Section Ag2SnS3–AgSbS2

2020 ◽  
Vol 65 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Sh. H. Mammadov ◽  
A. N. Mammadov ◽  
R. C. Kurbanova
Keyword(s):  
Binary Section ◽  
Quasi Binary Section
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