Liquid Fe-Mn Research Articles

Electrical Resistivity of Liquid Fe–Mn Alloys

Electrical Resistivity of Liquid Fe–Mn Alloys

Investigation of Two Immiscible Liquids Wetting at Elevated Temperature: Interaction Between Liquid FeMn Alloy and Liquid Slag

The goal of the current work is to develop a methodology to study the wetting behaviour of two immiscible liquids at high temperatures, and to investigate the parameters which influence the wetting properties. The wetting behaviour between synthetic FeMn alloy and synthetic slag has been investigated using the sessile drop technique. Two experimental procedures were implemented under both Ar and CO atmospheres: (a) FeMn alloy and slag placed next to each other on a graphite substrate; and (b) one droplet dropped on top of the other. FactSage is applied to calculate reactions and their equilibrium. The current work presents and demonstrates the suggested methodologies. The results indicate that the wetting between slag and FeMn alloy is relatively stable at temperatures up to 100 K above their melting points, regardless of the droplet size and atmosphere. MnO reduction is accelerated at higher temperature, especially in CO, thus increasing the wetting between FeMn alloy and slag, eventually fusing together. At even higher temperature, slag separates from FeMn alloy due to changing chemical composition during non-equilibrium MnO reduction.

Resistivity of Fe–Mn–C Melts

The resistivity of liquid Fe–Mn–C alloys containing from 5 to 25 wt % manganese and from 0.4 to 2.2 wt % carbon has been measured by the rotating magnetic field method. The measurements have been made during heating from 1340 to 1810°C and subsequent cooling of the samples. The resistivity of the melts during heating was considerably lower than that during subsequent cooling, which was accompanied by a decrease in the temperature coefficient of resistivity. The temperature dependence of resistivity for some of the alloys has been found to have an anomaly in the form of a break during heating to temperatures in the range 1550–1680°C. The addition of manganese and carbon has been shown to influence the resistivity of the melts and its temperature coefficient. We have calculated the effective resistivity of a liquid alloy with the composition (wt %) Fe–10Mn–1C as a heterogeneous system using analytical relations for conductivity of inhomogeneous media, a unit-cell method, and geometric models of isolated and interpenetrating inclusions. The temperature t* = 1730°C thus obtained for the transition from isolated to interpenetrating inclusions in the Fe–10Mn–1C melt agrees with the experimentally determined temperature t* = 1680°C of the beginning of the portion common to the temperature dependences of resistivity obtained during heating and cooling. The temperature 1540°C of the transition from isolated to interpenetrating inclusions agrees with the experimentally determined temperature 1550°C corresponding to the break in the temperature dependence of resistivity.

Characteristics of AlN inclusions in low carbon Fe–Mn–Si–Al TWIP steel produced by AOD-ESR method

Argon oxygen decarburisation–electroslag remelting (AOD-ESR) process has been well used to produce the Fe–Mn–Si–Al twinning induced plasticity steel (TWIP) steels. The characteristics of AlN inclusions formed in TWIP steels after AOD refining, ESR and forging process were investigated by scanning electron microscopy and X-ray energy dispersive spectrometry. An automated program called ‘INCAFeature’ was used to collect statistics of inclusion characteristics. Great differences on the amount, distribution and morphologies of AlN inclusions were observed in AOD ingots, ESR ingots and forgings. The dominating inclusions in AOD ingots are mainly single Al(O)N and MnS(Se)–Al(O)N aggregate, accounting for 66.7% of the total inclusions. After the ESR process, AlN inclusions in all size range significantly decreased, which were rarely observed in ESR ingots. Thermodynamic calculations show that AlN inclusions can precipitate in the liquid Fe–Mn–Si–Al TWIP steels, which is different from the viewpoint of literatures that the precipitation of AlN inclusions took place at solidifying front or solid phase. Furthermore, the thermodynamic calculation result has been verified by high temperature laser scanning confocal microscope experiments.

Nitrogen solubility in high manganese-aluminum alloyed liquid steels

The nitrogen solubility in liquid Fe-Mn and Fe-Mn-Al alloys has been measured by the gas-liquid metal equilibration technique utilizing a high frequency induction furnace under the nitrogen partial pressures of 0.1 to 0.8 atm in the temperature range of 1773 to 1873 K. The variation of the nitrogen solubility with the addition of manganese was measured by sampling and in-situ analysis of nitrogen content. Manganese significantly increased nitrogen solubility in liquid Fe-Mn and Fe-Mn-Al alloys. The nitrogen dissolution followed the Sieverts’ law for liquid Fe-Mn alloys contained manganese up to 26 mass%. Using the Wagner’s interaction parameter formalism, the experimental results were thermodynamically analyzed to determine the first- and second-order interaction parameters of manganese and aluminum on nitrogen in high Mn-Al alloyed liquid steels. No temperature dependence of these values was observed in the temperature range of 1773 to 1873 K. eNMn = −0.023, rNMN = 0 rNMn,Al = 0 (Mn≤26 mass%, Al≤0.4 mass%, 1773–1873 K).

Influence of Slag Basicity and Temperature on Fe and Mn Distribution between Liquid Fe–Mn–Ca–O–S Matte and Molten Slag

Influence of Slag Basicity and Temperature on Fe and Mn Distribution between Liquid Fe–Mn–Ca–O–S Matte and Molten Slag

Effect of surface adsorption of carbon on the surface tension of liquid Fe–Mn–C alloys

The influences of temperature, manganese, and carbon on the surface tension of liquid ternary Fe–Mn–C systems were investigated. The measurements were carried out with the sessile drop method in the temperature range of 1653–1834 K. The manganese and carbon contents were changed between 4.79–9.89 and 1.07–4.20 wt%, respectively. It was demonstrated that the surface tension varied as a linear function of temperature for all the examined samples. With increasing manganese content, the surface tension decreased. When the weight fraction of manganese with respect to iron was fixed, the surface tension decreased with increasing carbon content. From thermodynamic consideration, it was considered that carbon preferentially adsorbed on the metal surface as carbon atoms rather than manganese carbide.

Influence of Partial Pressure of Sulfur and Oxygen on Distribution of Fe and Mn between Liquid Fe-Mn Oxysulfide and Molten Slag

The authors proposed an innovative process for recovering Mn from steelmaking slag. The process starts with the sulfurization of steelmaking slag to separate P from Mn by the formation of a liquid sulfide phase (matte). Then, the obtained matte is weakly oxidized to make a Mn-rich oxide phase without P. High-purity Fe-Mn alloys can therefore be produced by the reduction of the Mn-rich oxide phase. However, to the authors’ knowledge, the sulfurization of molten slag containing P and Mn has not been sufficiently investigated. It was recently found that P was not distributed to the matte in equilibrium with the molten slag. To gain knowledge of the process’s development, it is important to investigate the influence of the partial pressures of sulfur and oxygen on the equilibrium distribution of Mn and Fe between the matte and the molten slag. In the current work, a mineralogical microstructure analysis of the matte revealed that the existence of the oxysulfide and metal phases was dependent on the partial pressure of sulfur and oxygen. The Mn content of the matte increased with partial pressure of sulfur while the O content of the matte decreased. In contrast, the ratio of Mn/Fe in the matte was constant when the metal phase of the matte was observed at a log $$ P_{{{\text{O}}_{2} }} $$ below −11. These results also corresponded to the relationship between the activity coefficient ratio of MnS/FeS and the mole fraction of MnS/FeS in the matte. The γ MnS/γ FeS value decreased exponentially as the mole fraction of MnS/FeS increased.

Density and Surface Tension of Liquid Fe-Mn Alloys

The density and surface tension of liquid Fe-Mn alloys were determined by using the sessile drop method at 1823 K (1550 °C). The density of liquid Fe-Mn alloys decreased with increasing Mn content. When the molar volume was plotted with respect to the mole fraction of Mn, a linear relationship was obtained. Consequently, it was found that there is no excess volume in liquid Fe-Mn alloy. The surface tension of liquid Fe-Mn alloys was found to decrease with increasing Mn content. The current experimental data were higher than the reported results but close to the calculated results using Butler’s equation.

Critical evaluations and thermodynamic optimizations of the Mn–S and the Fe–Mn–S systems

Critical evaluations and thermodynamic optimizations of the manganese–sulfur binary system and iron–manganese–sulfur ternary systems have been carried out over the entire composition range from room temperature to above the liquidus temperature. The Gibbs energies of all available phases have been thermodynamically modeled, and model parameters have been optimized in order to reproduce all available and reliable experimental data simultaneously within experimental error limits. For the liquid phase, the Modified Quasichemical Model (MQM) in the pair approximation is employed in order to properly take into account short-range-ordering in the phase. Thermodynamic model parameters of binary liquid Fe–S using the MQM and those of binary liquid Fe–Mn using the random-mixing model available in the literature are combined with those of binary liquid Mn–S using the MQM from the present study, in the framework of the MQM, in order to estimate Gibbs energy of ternary liquid Fe–Mn–S. Observed ternary solid solutions: (Mn, Fe)S and Fe 1 − x S are modeled using simple random-mixing model.

Reevaluation of the Fe-Mn phase diagram

New results for the enthalpy of mixing of liquid Fe-Mn alloys, the enthalpy of formation of γ-Fe-Mn solid solutions and the heat capacity of α-Fe-Mn and γ-Fe-Mn alloys obtained by isoperibolic calorimetry and differential thermal analysis (DTA) measurements have been used for the reassessment of the molar Gibbs energy of the various phases of the Fe-Mn system. Experimental information about martensitic transformation temperatures in Fe-Mn alloys published recently was incorporated in the updating of the occurring metastable equilibria. The present reevaluation results in a good fit with all available experimental data and is compared with the results of previous assessments.

Enthalpy of formation and heat capacity of Fe-Mn alloys

The partial and integral enthalpies of mixing of liquid Fe-Mn alloys were measured as a function of the atomic fraction of iron (x) within the range of 0≤x≤0.45 at 1700±5 K, using a laboratory-built, high-temperature isoperibolic calorimeter. The minimum integral enthalphy of mixing at x=0.5 is about −820±45 J mol−1. The enthalpy of formation of solid γ-Fe-Mn alloys with 30.0, 40.0, 50.0, and 57.0 at. pct Mn was determined indirectly, using the same calorimeter, by dissolving these alloys in liquid aluminium at 1409±3 K, and the minimum value amounts to −1940±70 J mol−1 at x=0.5. The heat capacities of these alloys as well as the heat capacity of pure iron and α-Fe-Mn alloys with 0.95, 2.03, 2.73, and 4.30 at. pct Mn, were measured by a differential thermal analysis (DTA) technique and are described using a new analytical representation of the magnetic contribution. The composition dependencies of heat content, Curie and Neel temperatures, enthalpy of formation of α-Fe-Mn alloys, magnetic contribution to the enthalpy of pure Fe and its change due to the addition of Mn, as well as the change of enthalpy upon the γ → α transformation, were deduced from the experimental data. The results obtained were compared with experimental information available in the literature.

Nitrogen concentration in liquid Fe-Mn alloys at high pressure

The U.S. Bureau of Mines has been studying the effects of increasing the N concentration in Fe alloys as an effective technique for increasing mechanical properties and improving corrosion resistance. N concentration in liquid Fe- Mn alloys was determined as a function of N pressure (1 to 2000 bars) and Mn concentration (0 to 30 wt.%). Samples were melted in a hot- isostatic- pressure furnace using N as the pressurizing gas. Measured N concentration in the solidified alloys was determined to be the same as that in the melt. Deviations from Sieverts’ law were observed at higher pressures and Mn concentrations. Correlation techniques that account for the effects of pressure on the N concentration.

Spinel deoxidation equilibria in the Fe—Mn—Al—O system – experiment and computation

The concentration and chemical potential of oxygen in liquid Fe—Mn alloys equilibrated with the spinel solid solution, (Fe, Mn)Al2+2xO4+3x, and α‐Al2O3 have been determined at 1873 K as a function of manganese concentration. The composition of the spinel phase has been determined using electron probe microanalysis. The results are compared with data reported in the literature. The deoxidation equilibrium has been computed using data on free energy of solution of oxygen in liquid iron, free energies of formation of hercynite and galaxite, and interaction parameters reported in the literature. The activity‐composition relationship in spinel solid solution was derived from a cation distribution model. The model is in excellent agreement with the experimental data on oxygen concentration and potential and the composition of the spinel phase.

Activities of Mn in solid and liquid Fe-Mn alloys

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Electronic structure of liquid iron alloys with manganese, chromium, and vanadium

Electrical resistivity of liquid FeCr, FeV, and FeMn alloys has been measured in the concentration range between 0 and 70% (by weight) of the dopping element, and over the temperature interval from tmelting to 1750°C. Using the Faber-Ziman-Evans method, concentration dependences of the electrical resistivity of liquid FeCr, FeV, and FeMn alloys have been calculated. Concentration dependences of the number of electrons per atom have been estimated.

Activity of manganese in liquid Ni-Mn alloys

Manganese is usually present as a minor component in alloys designed for high temperature oxidation resistance, and promotes the formation of protective spinel layers. Although thermodynamic data on liquid Fe-Mn alloys are well established, 1 there is a lack of corresponding experimental information regarding Ni-Mn alloys. Available data on solid Ni-Mn alloys have been evaluated by Hultgren et al.1 A solid state emf cell, with yttria doped thoria as the electrolyte and a mixture of Cr + Cr203 as the reference electrode, is employed in this study for measurement of the activity of manganese in the Ni-Mn system at 1683 K, for 0.4 > Xun > 0.05. The liquid alloy is contained in an alumina crucible and saturated with MnA12+2,O4+3x. The cell can be represented as:

等圧法による溶融Fe-Mn合金中のMnの活量の測定

The isobaric method with an alumina capsule has been developed to measure the activity of manganese in liquid Fe-Mn alloys at a satisfactory equilibrium state. The measurements have been made at 1843 K for NMn=0.09∼0.77. The activity of manganese shows a slight positive deviation from Raoult’s law, and the activity coefficient of manganese, γMn, is expressed by the following equation:(This article is not displayable. Please see full text pdf.) \ oindentThe attivity coefficient of manganese, γMn°, and the interaction parameter, εMn(Mn), at infinite dilute solution are 1.45 and −0.74, respectively.These results were in good agreement with the results of Sanbongi et al. obtained by the electromotive force method and those of Steiler et al. by the transportation method.

Kinetics of Nitrogen Desorption of Liquid Iron, Liquid Fe-Mn and Fe-Cu Alloys under Reduced Pressures

Kinetics of Nitrogen Desorption of Liquid Iron, Liquid Fe-Mn and Fe-Cu Alloys under Reduced Pressures

減圧下における溶鉄, 溶融Fe-MnおよびFe-Cu合金の脱窒速度

減圧下における溶鉄, 溶融Fe-MnおよびFe-Cu合金の脱窒速度