Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. I. Crystalline state of Fe–Mo melt-spinning alloys

Velikanova, Т. Ya.; Karpets, M. V.; Kuprin, V. V.; Турчанин, М. А.

doi:10.1007/s11106-010-9206-8

Cited by 8 publications

(3 citation statements)

References 13 publications

(18 reference statements)

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“…In the first part of this study [3], the metastable π-phase with β-Mn structure was identified in meltspinning 63Fe37Mo alloys. Besides this phase, μ-and σ-phases, bcc solid solutions rich in iron (α 1 ) and molybdenum (α 3 ), and metastable intermediate bcc phase (α 2 ) were revealed on both the contact and free surfaces of the melt-spinning ribbons.…”

Section: Abstract Thermodynamic Modeling Fe-mo System Metastable Phmentioning

confidence: 99%

“…Under this combination of thermodynamic and kinetic approaches, one of the ways is to calculate metastable phase diagrams, one or several phases being excluded from consideration. It is assumed that the formation of phases under these conditions (for example, in rapid quenching) is impossible or difficult due to kinetic features of the process.In the first part of this study [3], the metastable π-phase with β-Mn structure was identified in meltspinning 63Fe37Mo alloys. Besides this phase, μ-and σ-phases, bcc solid solutions rich in iron (α 1 ) and molybdenum (α 3 ), and metastable intermediate bcc phase (α 2 ) were revealed on both the contact and free surfaces of the melt-spinning ribbons.…”

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confidence: 99%

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Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. II. Thermodynamic modeling of Fe–Mo metastable states

Velikanova

Karpets

Турчанин

et al. 2010

Powder Metall Met Ceram

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The CALPHAD method is used for the thermodynamic modeling of metastable phase transformations in the Fe-Mo system. The relative thermodynamic stability of metastable α and β Mn-like phases and stable phases of the system are assessed. The Gibbs energy of intermetallic compounds with a homogeneity range is described within the Compound Energy Formalism. The calculated versions of Fe-Mo metastable phase diagrams interpret correctly the phase relationships in high-speed solidification of 63Fe37Mo alloy. Keywords thermodynamic modeling, Fe-Mo system, metastable phase diagrams, Mn-like phasesInformation on phase equilibria in the Fe-Mo system is important for understanding the behavior of materials even when thermodynamic equilibrium is not reached since it shows the direction in which alloys undergo phase transformations. During some processes, materials can be produced in conditions far from equilibrium. An example of such processes is rapid melt quenching. In this case, the equilibrium phase diagram can hardly be used and the analysis may be based on the thermodynamic assessment of the system in general taking into account the kinetics of the processes [1,2]. Under this combination of thermodynamic and kinetic approaches, one of the ways is to calculate metastable phase diagrams, one or several phases being excluded from consideration. It is assumed that the formation of phases under these conditions (for example, in rapid quenching) is impossible or difficult due to kinetic features of the process.In the first part of this study [3], the metastable π-phase with β-Mn structure was identified in meltspinning 63Fe37Mo alloys. Besides this phase, μ-and σ-phases, bcc solid solutions rich in iron (α 1 ) and molybdenum (α 3 ), and metastable intermediate bcc phase (α 2 ) were revealed on both the contact and free surfaces of the melt-spinning ribbons. The formation of the χ-phase (α-Mn type) and high-temperature (R) and lowtemperature (λ) phases in melt-spinning 63Fe37Mo ribbons was suppressed during our experiment. In addition, the homogeneity range of the σ-phase was substantially extended toward the iron-rich composition range, which was testified by the noticeable decrease in its lattice parameters.The presence of the μ-, σ-, and bcc phases in melt-spinning 63Fe37Mo ribbons agrees with the Fe-Mo phase diagram (Fig. 1a, b). The formation of the metastable π-phase, which is absent in the phase diagram, during

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Section: Abstract Thermodynamic Modeling Fe-mo System Metastable Phmentioning

confidence: 99%

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confidence: 99%

Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. II. Thermodynamic modeling of Fe–Mo metastable states

Velikanova

Karpets

Турчанин

et al. 2010

Powder Metall Met Ceram

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“…Computational thermodynamic approaches using the CALPHAD approach (calculation of phase diagrams) are widely used, and allow you to calculate equilibrium and metastable phase transformations based on a set of mutually agreed thermodynamic parameters of system phases [14]. The thermodynamic properties of each phase that takes part in the transformations are described by appropriate models, which for phases of constant composition should take into account the temperature dependence, and, in addition, for phases that have a region of homogeneity, the temperature-concentration dependence of the Gibbs energy [15]. This approach was used to model the behavior of the multicomponent reacting systems Nb-Ni-Si [16], Cr-Mn-Si [17], C-Nb-Mo [18], B-Fe-Ti [19], B-Mo-Ti [20], B-Mo-Nb [21], V-Ti-B [22], and many others, and allowed modeling of the corresponding state diagrams.…”

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confidence: 99%

Physicochemical Conditions of Boron–Siliconizing of Molybdenum-Based Alloys in Chlorine and Fluorine Medium

Loskutova,

Scheffler,

Ivanov

et al. 2024

Metals

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The physicochemical conditions of the siliconizing and boron–siliconizing processes of molybdenum-based alloys in a closed reaction space in an environment of chlorine and fluorine at reduced pressure were studied. Theoretical calculations of the equilibrium composition of systems with the participation of silicon, boron, molybdenum, nitrogen, oxygen, chlorine, and fluorine were carried out, which made it possible to determine the influence of process parameters (temperature, composition of the reaction medium) on the probable phase composition of the obtained coatings. Based on thermodynamic calculations, the composition and rational consumption of the initial powders and the temperature intervals of the chemical heat treatment (CHT) during the complex saturation of molybdenum-based alloys with silicon and boron were modeled. It was established that it is advisable to use chlorine as an activator, which leads to the formation of molybdenum chlorides MoCl4 and MoCl3 in the composition of the gas phase and can indicate the flow of exchange reactions between chlorides and the matrix of the processed material in the reaction space. The rational saturation temperature of alloys based on molybdenum with silicon and boron is determined—1100–1250 °C. The possibility of the existence of condensed phases MoSi2, MoB2.15, B6Si, MoB1.65, and MoB is shown.

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Stability of the β-Mn structure in rapidly quenched Fe–Mo–Cr–C alloys at high temperatures

Velikanova

Karpets

2011

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High-temperature x-ray diffraction (HT-XRD) is used to study the evolution of phase states of arcmelted and spinning 51.9Fe11.1Mo26.3Cr10.7C (at.%) alloys in the temperature range 293-1573 K. It is established that α-and β-Mn-like phases (χ and π, respectively) and solid solutions based on α-and γ-Fe identified by HT-XRD in the temperature range 293-978 K are metastable. A diffusion-free method for mutual transformations of Mn-like phases in the temperature range 873-978 K is proposed. It is shown that increase in temperature in HT-XRD conditions stabilizes metastable Mn-like phases. It is experimentally established, for the first time, that a stable β-Mn-like phase exists near the solidus in the Fe-Mo-Cr-C system. It is concluded that congruent crystallization is a way of forming a stable π-phase of composition Fe 5 MoCr 2.5 C. It is found out that a stable χ-phase and equilibria with its participation, α + η + M 23 C 6 + χ and χ + α + π + L, exist in the temperature range 1473-1523 K in the Fe-Mo-Cr-C system. It is determined that decomposition and/or mutual transformations of metastable Mn-like phases in 51.9Fe11.1Mo26.3Cr10.7C alloys occur at T ≈ 978 K, which is close to the temperature of α-Mn ⇔ β-Mn polymorphic transformation in pure manganese.

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Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. I. Crystalline state of Fe–Mo melt-spinning alloys

Cited by 8 publications

References 13 publications

Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. II. Thermodynamic modeling of Fe–Mo metastable states

Manganese-like metastable phases in the Fe–Mo system: experimental study and thermodynamic modeling. II. Thermodynamic modeling of Fe–Mo metastable states

Physicochemical Conditions of Boron–Siliconizing of Molybdenum-Based Alloys in Chlorine and Fluorine Medium

Stability of the β-Mn structure in rapidly quenched Fe–Mo–Cr–C alloys at high temperatures

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