Pure Liquid Iron Research Articles

The precipitation diagram of [Ce]‐[O]‐[S] in liquid iron and its application

A space precipitation diagram of [Ce]‐[O]‐[S] in pure liquid iron has been constructed utilising recent experimental thermodynamic data gathered on allied equilibrium systems of RE‐O, RE‐S and RE‐O‐S. A quantitative correlation between the activities of oxygen, sulphur and the constitution of the formed RE inclusions has been found. This correlation was theoretically evaluated through thermodynamic calculation and verified by experimental data concerned with the activities of oxygen and sulphur in liquid iron and the composition of the formed RE inclusions.

Optical properties of liquid nickel and iron

The optical properties of pure liquid nickel and iron were investigated in the energy range 1.2--3.5 eV. Nickel and iron specimens were electromagnetically levitated, melted, and purified of residual oxide contaminants by heating to elevated temperatures and/or reacting the liquids with pure hydrogen. An automated dual-detector rotating analyzer ellipsometer with a pulsed-dye-laser light source was employed to measure the optical properties. Measurements were obtained over the full energy range at 1764 K for nickel and at 1890 K for iron. Liquid nickel exhibited a broad minimum in the optical conductivity at about 2.2 eV photon energy, similar to the minimum that the solid exhibits at about 3 eV. The optical conductivity of liquid iron increased smoothly from the UV to the IR except in the vicinity of 2.25 eV where a 10% decrease was observed. This behavior is quite different from the solid, which shows a broad peak in the optical conductivity at about 2.4 eV and decreasing conductivity values towards the UV and IR. A broad minimum was also observed in the real part of the dielectric constant for liquid iron, at about 2.0 eV, where a maximum occurs for the room-temperature ferromagnetic solid. The optical properties and spectral emissivities of liquid nickel and iron are discussed with respect to available literature data for both the solid and liquid.

Control of the aluminium-oxygen reaction in pure iron melts

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Deoxidation Equilibrium of Hafnium in Liquid Iron, Nickel and Iron-Nickel Alloys.

The deoxidation equilibrium of hafnium in liquid iron, nickel and iron-nickel binary alloys has been studied at the temperature ranges from 1873 to 1973 K using hafnia crucibles. The effect of temperature on the equlibrium constant of the deoxidation reaction in liquid iron with hafnium was found to be: log KHf(Fe)(=aHf·aO2)=-35840/T+11.39 while the deoxidation product in iron was expressed as follows: logK'Hf(Fe) (=[%Hf] [%O]2)=logKHf (Fe)+5.85(2[%Hf]+11.1 [%O]) (0.01-0.1 mass% Hf) The temperature dependence of the equilibrium constant of the deoxidation in liquid nickel was determined as the expression. log KHf(Ni)=aHf·aO2= –33800/T+8.40 in the meantime, the deoxidation product in nickel was given by: log K'Hf (Ni) (=[%Hf] [%O]2)=log KHf (Ni)+9.75 (2 [%Hf]+11.1 [%O]) (0.002-0.1 mass% Hf) The deoxidation of iron-nickel binary with hafnium was measured over whole concentration ranges of the binary system at temperatures of 1873 and 1923 K. The activity coefficients of oxygen and hafnium in the binary based on pure liquid iron were given by the following expression: log fO(Fe)Ni+ 1/2 log fHf(Fe)Ni=0.005 [%Ni] below 60 mass% of nickel, while the activity coefficients on the nickel basis were expressed by: log fO(Ni)Fe+ 1/2 log fHf(Ni)Fe= –0.025 [%Fe] below 10 mass% of iron.

Thermodynamic study of Fe-Ta and Fe-Nb alloys by means of the Knudsen cell mass spectrometry.

The activity of iron in the Fe–Ta and Fe–Nb alloys at 1 873 K was determined by means of the Knudsen cell mass spectrometry. A modified internal standard method was employed, in which a piece of pure iron foil placed on the sample surface in the Knudsen cell served as the internal standard material. The ion intensity of iron from the foil was first measured at several temperatures before the alloy sample and the foil melted together. The ion intensity from pure solid iron thus obtained was extrapolated to give ion intensity from pure liquid iron at higher temperatures. The temperature of the sample was then raised to form uniform liquid alloy and the ion intensity of iron from the alloy was measured. The activity of iron in the alloy was determined by comparing the ion intensities from pure iron and from alloy.The activities of Ta and Nb were derived from that of iron by integrating the Gibbs-Duhem equation. The activity coefficients of Ta and Nb in the infinitely dilute solution with liquid pure metal as the standard state were also calculated. The interaction parameters were determined. These results were compared with those of elements adjacent to Ta and Nb in the periodic table.Invariant reactions appeared in the Fe–Ta binary alloy system at high temperature were investigated by employing the ion intensity thermal analysis, in which the ion intensity represented the temperature of the sample. Heat treatment and metallographic study was also carried out for the identification and composition determination of phases.

Equilibria between the rare earth elements, oxygen and sulfur, in molten iron

The values of Kce2o2s and KCe2S 3 reported in the literature are greater than they should be. Such a situation has arisen because in the calculation of the respective equilibrium constants, the total amount of Ce, O, and S each contained in the samples has been used instead of only the dissolved amounts. The relationships between equilibrium constants and temperatures of Ce-O-S, Y-O-S, Nd-O-S, La-O-S, and Ce-S in pure liquid iron have been determined by using a previously developed experimental method. The activity interaction coefficients, e N~, e~, and es La at different temperatures have been determined. The standard free energies of formation of Nd202S, YzO2S, and Ce2S 3 have been calculated by using the relevant experimentally derived parameters. I. INTRODUCTION THE rare earth elements are strong deoxidizers and desulfurizers. In liquid steels treated by rare earth elements, rare earth oxides and sulfides and oxysulfides, such as RE2OzS, are formed. The rare earth oxysulfides are found more often in steel ~-4 than the sulfides or oxides. Nevertheless, little work has been done on the equilibrium of RE-O-S in molten steel until recently. Considerable research has dealt with the problems on the equilibrium constant of low-valency rare earth sulfide in molten iron, but there is almost no information on the determination of equilibrium constant for high-valency rare earth sulfides. Highly sensitive radioassay was adopted to determine the amount of dissolved RE and S in the iron specimens by means of electrolyzing the specimens in organic electrolyte at low temperature to remove the rare earth inclusions. The oxygen activity in molten iron was measured by a solidelectrolyte oxygen-probe made of ZrOz(MgO) tube so as to determine accurately the equilibrium constants of RE-O-S and RE-S.

Electrical conductivity of molten FeNiSC core mix

The electrical conductivity of liquid (Fe 90Ni 10) 3S 2 saturated with 2.6 weight percent carbon averages 2.7·10 5 mho/m at 1000°C and zero pressure. This may imply a slightly lower electrical conductivity for the earth's core than that obtained by extrapolating the properties of pure liquid iron and solid iron alloys to core pressures and temperatures. Although a sulphur-rich core would have a smaller proportion of sulphur, the effect of lowering the sulphur content of the FeNiSC liquid to about 15 weight percent would be unlikely to increase the conductivity above 5·10 5 mho/m.

Surface tension of pure liquid and supercooled iron

Surface tension of pure liquid and supercooled iron

Surface tension measurements on pure liquid iron and nickel by an oscillating drop technique

A novel experimental technique for the measurement of surface tension of molten metals has been developed. It is based on the Rayleigh equation which relates frequency and surface tension for an oscillating drop. A systematic study has shown this equation to be valid for a liquid metal droplet levitated electromagnetically in an inert flowing gas with no prior calibration required. It is, therefore, an absolute method. The frequencies of oscillation of droplets of pure iron and nickel in a 6 pct H2-He gas mixture were measured by high speed cinematography. Surface tensions were obtained for temperatures of 1550° to 1780°C for iron and 1475° to 1650°C for nickel.

Hydrogen transport in stagnant molten iron

A new experimental method is described for the study of gas absorption in liquid metals. The technique involves the sudden admission of the gas into a previously evacuated tube containing a column of stagnant liquid metal. Following a short initial period of pressure instability (< 10 sec), absorption rates can be accurately followed by monitoring changes in gas pressure (or volume) using a differential pressure transducer. In the present work, the solution of hydrogen in pure liquid iron was studied and confirmed to be a diffusion controlled process. The mean diffusion coefficient measured for hydrogen absorption in pure iron at 1 atm pressure over the temperature range 1550° to 1720°C was 8.76 x 10−4 sq cm sec−1. This figure is about 35 pct lower than previously reported values by Parlee and coworkers.9−10

Electrical resistivity of the earth's core

Allowance for effect of impurities in the iron of the earth's fluid core increases its electrical resistivity by a factor of about 10 over previous estimates, to a new preferred value 3 × 106 emu (3 × 10−5 ohm m). Extrapolations of the resistivity of pure liquid iron to probable temperatures and pressures of the core only involve factors of 1.6 and 1.3 and are slight compared with the impurity effect. The plausible range of values is 106 to 2 × 107 emu, which could be substantially narrowed by resistivity measurements on iron alloys in the liquid state. The new estimate strongly favours precessional torques rather than convection as the driving mechanism for the geomagnetic dynamo.