scholarly journals Phase equilibria in the MnO-Mn2O3-FeO-Fe2O3-Sb2O3-Sb2O5 System in Air at 1200℃

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
BG Golovkin
Keyword(s):  
Phase Diagram ◽  
Phase Composition ◽  
Phase Equilibria ◽  
Normal Pressure ◽  
X Ray ◽  
Densitometric Analysis ◽  
Temperature Range ◽  
Air Atmosphere ◽  
Different Temperatures ◽  
New Phase

Using the methods of X-ray phase and X-ray Densitometric analysis, the phase equilibria between oxides of manganese, iron and antimony have been investigated in an air atmosphere at temperatures up to 1250? in an air mosphere at normal pressure. The phase diagram of the system at 1200? was built MnO-Mn2O3-FeO-Fe2O-Sb2O3-Sb2O5. A new phase was found Mn12-2x,sup>2+Fe2x2+Sb3+Sb55+O26(0?x?1), with edge compositions FeMn5Sb3O13 and Mn6Sb3O3 (a=8.5003?0.0025Å; b=8.0064?0.0025Å; c=11.5779?0.0025Å; Z = 3; ?obs. = 5.7 g/cm3; ?calc = 5.6991 g/cm3). The phase exists in the temperature range 1180-1230oC and can be obtained by quenching, but always with a large admixture of Mn2Sb2O7 and spinel Mn112+Mn133+Sb93+O44.The reason for this behavior is that air molecules have different temperatures, as a result of which the phase composition of the reaction mixture cannot be strictly related to one temperature, and different phases can be stable at different temperatures.

scholarly journals Phase Equilibria in the In2O3-WO3 System

2002 ◽  
Vol 756 ◽  
Author(s):  
Annette P. Richard ◽  
Doreen D. Edwards
Keyword(s):  
Phase Equilibria ◽  
Binary Oxide ◽  
X Ray Diffraction ◽  
Subsolidus Phase ◽  
X Ray ◽  
Temperature Range ◽  
Oxide Phases ◽  
Phase Relationships

ABSTRACTThe subsolidus phase relationships in the In2O3-WO3 system at 800 – 1400°C were studied by X-ray diffraction. Two binary oxide phases – In2(WO4)3 and In6WO12 – are stable in air over the temperature range of 800 – 1200°C. Preferential volatilization of WO3 prevented the determination of phase equilibria above 1300°C.

scholarly journals Stability of ferroic phases in the highly piezoelectric Pb(ZrxTi1−x)O3ceramics

2007 ◽  
Vol 64 (1) ◽  
pp. 192-203 ◽  
Author(s):  
Dhananjai Pandey ◽  
Akhilesh Kumar Singh ◽  
Sunggi Baik
Keyword(s):  
Phase Diagram ◽  
Room Temperature ◽  
Physical Property ◽  
Rhombohedral Phase ◽  
Multiple Diffraction ◽  
Pzt Ceramics ◽  
X Ray ◽  
Space Groups ◽  
The Stability ◽  
New Phase

The morphotropic phase boundary in the phase diagram of the technologically important Pb(ZrxTi1−x)O3(PZT) ceramics has been traditionally believed to separate ferroelectric tetragonal and rhombohedral phase regions. This old picture has come under close scrutiny during the last eight years following the discovery of new monoclinic phases in theCmandCcspace groups. This article presents a brief overview of these discoveries in which the use of multiple diffraction probes (X-ray, electron, neutron diffraction) in conjunction with physical property measurements has played a crucial role. A new phase diagram of PZT showing the stability fields of these structures below room temperature is also presented.

scholarly journals PHASE DIAGRAM OF THE TlTe–Tl9TmTe6 SYSTEM

2021 ◽  
pp. 18-22
Author(s):  
I.F. Mehdiyeva ◽  
Keyword(s):  
Phase Diagram ◽  
Phase Equilibria ◽  
Solid Solutions ◽  
X Ray Diffraction ◽  
X Ray

Phase equilibria in the TlTe–Tl9TmTe6 system were experimentally studied by methods of differential thermal and powder X-ray diffraction analyses. The system was found to be non-quasibinary due to the incongruent nature of both initial components melting, but it is stable below solidus and is characterized by formation limited solid solutions (2 mol%) based on Tl9TmTe6 are revealed in the system

scholarly journals Features of Magnetocaloric Effect in Er(Co-Fe)2 Laves Phases

2016 ◽  
Vol 1 (1) ◽  
pp. 5 ◽  
Author(s):  
M.S. Anikin ◽  
E.N. Tarasov ◽  
N.V. Kudrevatykh ◽  
M.A. Semkin ◽  
A.S. Volegov ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Composition ◽  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Concentration Increase ◽  
Laves Phases ◽  
X Ray ◽  
Temperature Range

<p>In this work the results of measurements of heat capacity (C<sub>P</sub>) and magnetocaloric effect (MCE) in Er(Co<sub>1-</sub><sub>х</sub>Fe<sub>х</sub>)<sub>2</sub> system in the concentration range 0.07 ≤ x ≤ 0.80 are presented. Phase composition was controlled by X-ray difraction analysis. Heat capacity was measured in the temperature range 77-320 K. MCE has been studied within the temperature range 5-670 K in magnetic fields up to 70 kOe. It was found that Fe concentration increase caused the table-like (plateau) MCE temperature dependence for both magnetic entropy change date and direct ∆T-effect measurements independently on Fe concentration. The possible reasons of such behavior are discussed.</p>

Crystal structure of adamite at high temperature

2016 ◽  
Vol 80 (5) ◽  
pp. 901-914 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
M. Boiocchi ◽  
A. M. Callegari
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Expansion ◽  
Cell Parameters ◽  
Temperature Range ◽  
Linear Evolution ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Increasing Temperature

AbstractStructural modifications with temperature of adamite, Zn2(AsO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and collapse of the crystal structure. In the temperature range 25–400°C, adamite shows positive and linear expansion. Axial thermal expansion coefficients, determined over this temperature range, are αa = 1.06(2) × 10–5 K–1, αb = 1.99(2) × 10–5 K–1, αc = 3.7(1) × 10–6 K–1 and αV = 3.43(3) × 10–5 K–1. Axial expansion is then strongly anisotropic with αa:αb:αc = 2.86: 5.38 : 1. Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the adamite structure accommodates variations in temperature. Expansion is limited mainly by edge sharing Zn(2) dimers along a and by edge sharing Zn(1) octahedra chains along c; on the other hand, connections of polyhedra along b, the direction of maximum expansion, is governed by corner sharing. Increasing temperature induces mainly an axial expansion of Zn(1) octahedron, which becomes more elongated, and no significant variations of the Zn(2) trigonal bipyramids and As tetrahedra. Starting from 400°C, deviation from a linear evolution of unit-cell parameters is observed, associated with some deterioration of the crystal, a sign of incipient dehydration. The process leads to the formation of Zn4(AsO4)2O.

Development of a Tool for Temperature Estimation From Microstructural Condition of a Nicoraly+Re Coating Applied on the Surface of Gas Turbine Hot Components

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Alessio Costa ◽  
Vacchieri Erica ◽  
Emma Barbareschi ◽  
Paola Guarnone ◽  
Alessandra Bonadei ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Gas Turbines ◽  
Residual Life ◽  
Intermetallic Phase ◽  
Service Temperature ◽  
Temperature Oxidation ◽  
Σ Phase ◽  
Temperature Range ◽  
Different Temperatures

The hot gas path components of gas turbines have to withstand to severe conditions in terms of high temperature oxidation, hot corrosion, and creep-fatigue phenomena. The evaluation of components residual life is an important matter for gas turbines producers and the estimation of service temperatures is a key tool for this evaluation. The most diffused methods to estimate service temperatures of gas turbines blades and vanes in Ni based superalloys are related to the microstructural evolution of the dispersed intermetallic phase γ′, Ni3Al. The aim of this work has been the determination of a tool to estimate service temperature on the basis of the microstructural evolutions of a NiCoCrAlY+Re coating. In order to obtain a deep characterization of the coating after exposure at different durations and temperatures, an extensive experimental test program has been planned. Samples of Ni based superalloys, covered by the investigated coating, have been aged in chamber furnaces in the temperature range 700 °C–1000 °C with durations up to 20,000 h. The microstructure of this coating is characterized by β phase, NiAl, which is the Al reservoir, embedded in the matrix, that is constituted by γ′ phase at low temperature and by γ phase over 900 °C. Moreover, electron back scattered diffraction and X-ray diffraction measurements on samples have revealed three classes of secondary phases: the first one has been identified as σ-Cr2Re3, the second one as Cr carbide-Cr23C6 and the third one as α-Cr. σ phase is very abundant at the lower temperatures while it disappears after long exposures at temperatures higher than 900 °C. The σ phase composition is different at different temperatures and the Re content in particular increases with the temperature. Starting from the σ phase composition determined at different temperatures, a tool has been constructed that relates the service temperature to the Re content in the same phase. The new tool has been applied to the analyses of different components. The results of the new method have been compared to those ones obtained with the method based on γ′ features, developed in the past through huge experimental campaigns. The agreement between the two methods is generally good, they can be used in a complementary way due to the fact that the γ′ one seems to be more suitable for high temperature ranges (T > 900 °C) where it gives a reliable estimation, while the σ method is more suitable in the temperature range 700 °C–900 °C.

scholarly journals The effect of carbon content and cooling rate on the structure of boron-rich Fe–B–C alloys

2020 ◽  
Vol 21 (2) ◽  
pp. 355-360
Author(s):  
E. V. Sukhova
Keyword(s):  
Phase Diagram ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Eutectic Reaction ◽  
Thermal Analyses ◽  
Two Phase ◽  
X Ray ◽  
Three Phase

The structural and phase composition of boron-rich Fe–В–С alloys in the concentration range of 9.0–16.0 % В, 0.001–1.7 % С, Fe – the balance (in wt. %) was investigated in this work. The cooling rate of the alloys was from 10 to 103 К/s. The methods of quantitative metallographic, X-ray, energy dispersive X-ray, and differential thermal analyses were applied. It was established that the maximal solubility of carbon in Fe2B hemiboride does not exceed 0.55 %, and that in FeB monoboride – 0.41 %. The alloys that belong to two-phase peritectic (Fe2(B,C)+Fe(B,C)) region, two-phase peritectic-eutectic (Fe2(B,C)+Fe(B,C)) region, and three-phase peritectic-eutectic (Fe2(B,C)+Fe(B,C)+C) region of the Fe–В–С phase diagram were distinguished depending on their structure. The appearance of an eutectic constituents in the investigated alloys was explained by transition of peritectic reaction L+Fe(В,С)®Fe2(В,С) to eutectic reaction L®Fe(В,С)+Fe2(В,С) within the temperature range of 1623–1583 К in the presence of carbon. With cooling rate increasing from 10 to 103 К/s, structural constituents tended to be fine, their volume fraction changed, microhardness and fracture toughness increased.

scholarly journals Исследование фазового состава интерфейсного слоя, полученного при горячем прессовании Cr и Si

2021 ◽  
Vol 55 (12) ◽  
pp. 1115
Author(s):  
Ф.Ю. Соломкин ◽  
А.Ю. Самунин ◽  
Н.В. Зайцева ◽  
Н.В. Шаренкова ◽  
Г.Н. Исаченко ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Composition ◽  
Low Temperature ◽  
Hot Pressing ◽  
Contact Boundary ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Medium Temperature ◽  
X Ray ◽  
Before And After

The possibility of synthesizing layers of the medium-temperature thermoelectric CrSi2 by hot pressing of the initial components (Cr and Si) has been investigated. The phase composition of samples obtained by hot pressing of Cr and Si before and after annealing in the region of their contact boundary has been investigated by X-ray analysis. It is shown that, under certain conditions, low-temperature synthesis of a CrSi2 layer with a thickness of 50 to 300 μm is possible at the interface between Cr and Si. The synthesis occurs at a temperature significantly lower than that given in the phase diagram, which opens up new technological possibilities for obtaining the CrSi2 compound.

Solid State Electrochemical Study of Phase Equilibria and Thermodynamics of the Ternary System Y-Fe-O at Elevated Temperatures

1979 ◽  
Vol 34 (4) ◽  
pp. 430-436 ◽  
Author(s):  
W. Piekarczyk ◽  
W. Weppner ◽  
A. Rabenau
Keyword(s):  
Phase Diagram ◽  
Solid State ◽  
Ternary System ◽  
Phase Equilibria ◽  
Elevated Temperatures ◽  
Free Energies ◽  
Ternary Compounds ◽  
Temperature Range ◽  
The Third ◽  
Galvanic Cell Technique

A solid state galvanic cell technique has been employed to determine the phase diagram of the ternary system Y-Fe-O in the temperature range from 900 to 1250 °C. Only electrical quantities need to be measured and the samples do not have to be quenched. YFeO3 and Y3Fe5O12 exist over the entire temperature range, whereas the third ternary compound YFe2O4-x is only thermodynamically stable above 1010 ± 9 °C. Above 1078 ± 15 °C YFe2O4-x comes into equilibrium with Y2O3.With the same experimental arrangement the standard Gibbs free energies of formation ⊿G f0 of the ternary compounds YFeO3, Y3Fe5O12 and YFe2O4 have been determined to be -1366.0 + 0.2525 X T kJ/mol (1173 ≦ T [K] ≦ 1523), - 4912.2 +0.9990 X T kJ/mol (1173≦T[K] ≦ 1523) and -1615.9 + 0.3068 x T kJ/mol (1283≦T[K] ≦ 1523) as functions of the temperature, respectively

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