For thermodynamic prediction, the deoxidation equilibrium of aluminum in Fe-36%Ni alloy was investigated by employing a cold crucible under an Ar gas atmosphere at 1 773 K. The interaction parameters between aluminum and oxygen by taking liquid Fe-36%Ni alloy as the basis (i.e., solvent) are evaluated as follows: within the composition range of [Al]Ͻ1 mass%. The equilibrium constant for reaction 2Al ϩ3O ϭAl 2 O 3(s) was obtained in the temperature range of 1 773 to 1 973 K by using data from the present study and from previous works reported:log K AO ϭ0.58Ϫ24 460/T The deoxidation equilibrium of aluminum in Fe-36%Ni can thus be thermodynamically described in the range of [Al]Ͻ1 mass% using both the first and second order interaction parameters as well as the equilibrium constant determined in this study.KEY WORDS: deoxidation equilibrium; equilibrium constant; interaction parameter; aluminum; nickel; deoxidation product, inclusion; cold crucible.teraction parameter between aluminum and oxygen based on liquid i.e., by investigating deoxidation equilibrium for aluminum in Fe-36%Ni under H 2 /H 2 O gas mixture at 1 973 K and the result is given in Table 1. However, their work was confined to a narrow range in low aluminum concentrations.The objective of the present study is to obtain the thermodynamic data of aluminum deoxidation equilibrium over a wide range of aluminum content covering up to 1 mass% Al in Fe-36%Ni alloy at 1 773 K. Liquid Fe-36%Ni is chosen as a base melt to avoid a separate consideration of nickel on other elements. The equilibrium constant as well as the first order and second order interaction parameters have been determined at 1 773 K. Experimental ProcedureElectromagnetic levitation-melting technique using a cold crucible was employed to study aluminum deoxidation equilibrium in liquid Fe-36%Ni. The cold crucible is a copper crucible constructed in segments, each of which is water-cooled (flow rate: 20 l/min). A high frequency current (20 kW and 170 kHz) was applied to the coil surrounding the crucible.This non-contact levitation melting enables to avoid any contamination or side effect which could otherwise result from a container like alumina crucible. Furthermore, inclusion particles, which are deoxidation products, are completely exposed on the surface of the molten metal and accumulated at the bottom of the metal in the form of a thin film by gravity. Therefore, metal and oxide are perfectly separated from each other and hence all oxygen and aluminum existing in the metal can be regarded as solute, not in the form of oxide.The experimental apparatus is shown in Fig. 1. Gas purification trains and gas flow meters are also constructed. The melt temperature was measured using a two-color optical pyrometer calibrated preliminarily against a thermocouple (Pt-30%Rh/Pt-6%Rh).Nickel and iron of electrolytic grade and high purity aluminum (99.99 mass%) were used in preparing alloys. Master alloys of Fe-36%massNi and Fe-36%massNi-1%massAl were made in an alumina crucible using an induction fur...

Effects of hydrogen sulfide (1–3%) on the reduction rate of iron oxide pellets were investigated in temperature range of 800–1100°C. It was found that the reduction rate increased slightly with the addition of 1% H2S, whereas it decreased significantly with the addition of 3% H2S. The fractured surface of partially reduced pellets was observed by an optical microscope, a scanning electron microscope (SEM) as well as analyzed by an energy dispersion spectrometer (EDS). It is indicated that small amounts of sulfur may have promoted the formation of porous iron to accelerate the reduction rate, whereas the dense iron sulfide shells formed at higher H2S offered resistance to the intraparticle diffusion of reducing gas to significantly decrease the reduction rate of pellets.

For a successful stainless steelmaking process, it is necessary to reduce Cr oxide in slag, using ferrosilicon alloy, as quickly as possible. The effects of particle size on the melting rate of ferrosilicon alloy were investigated by monitoring melting behavior of ferrosilicon alloys both on stainless steel melt and on the slag using a video camera. The reduction experiment using an induction furnace of 50-kg capacity was also carried out. The experimental results indicated that the smaller the particle size, the shorter the melting time, and it is shorter on steel melt than on slag. It was found that the reduction rate is controlled by the melting rate at the initial stage of reaction, but after the initial stage, the transfer of chromium oxide controls the overall rate.

The interaction parameters of alloying elements on nitrogen in liquid Fe-Cr alloys containing niobium have been determined. The equilibrium nitrogen solubility in the liquid iron alloy was measured by metal-gas equilibrium technique under 0.04 to 1.0 atm of nitrogen atmosphere at 1 823 to 1 923K. Nitrogen solubility in Fe-Cr-Nb melts obeyed Sieverts' law for all compositions studied in present study.The results obtained are summarized as follows;(1) The solubility of nitrogen markedly increased with increasing chromium and niobium. The interaction parameters in liquid iron alloys containing 10-18 % of Cr and 0.2-2 % of Nb are obtained. (2) The solubility of nitrogen was lower at a higher temperature in Fe-Cr melts in this study. (3) Test results indicated that it is not likely to form niobium nitride in Fe-Cr-Nb-N alloys and it was confirmed by EDS.

The Fe-36 pct Ni alloy, exhibiting anomalously low thermal expansion over a wide temperature range, is used as a functional and electromagnetic material. [1] Since it is especially used as TV Shadow mask, the demand has rapidly increased. Manganese in the alloy is one of the important elements for the complex deoxidation. However, no data are available for the thermodynamic prediction of the manganese deoxidation equilibrium in this alloy.In most investigations [2][3][4][5][6] on thermodynamic aspects of deoxidation equilibrium in Fe-Ni alloys, the effect of nickel on activity coefficients of oxygen and deoxidizing elements in liquid iron have been evaluated by using their experimental results in Fe-Ni melts and the values recommended by Fig. 1-Solubility of iron in magnesium-lithium melts at 700 ЊC as deter-JSPS, [7] which is primarily concerned with dilute solutions mined in this work.based on liquid iron as the solvent. Application of those data, good basically for dilute solutions to the case of high alloy steels such as Fe-36 mass pct Ni (Invar), is not considered to conform to the concept of Wagner's interaction parameters. [8] In order to overcome the irrelevance mentioned previously, the present study aims to obtain thermodynamic data by taking the solution of "liquid Fe-36 mass pct Ni" as the solvent melt, which basically eliminates separate consideration of the effect of nickel on other elements. This article deals with determination of thermodynamic data (equilibrium constant and interaction parameter) of manganese deoxidation equilibrium in the range of manganese content covering from 0.1 to 5 mass pct in Fe-36 pct Ni alloy at 1773 K.The electromagnetic levitation-melting technique using a cold crucible was employed to study manganese deoxidation equilibrium in liquid Fe-36 pct Ni. The cold crucible is a copper crucible manufactured by Crystalox Ltd. (Oxford, UK) (32 ϫ 10 Ϫ3 m i.d., 52 ϫ 10 Ϫ3 m o.d., and 135 ϫ 10 Ϫ3 m length) and constructed in multiple segments, each of which is water cooled (flow rate: 20 L/min). A high-frequency current (20 kW and 170 kHz) is applied to the coil surFig. 2-Solubility of iron in liquid magnesium (liquidus of solid iron) as rounding the crucible.determined in this work and as known from the literature. [3,4,5] This noncontact levitation melting enabled avoidance of any contamination or side effect resulting from a container material such as MnO crucible. Furthermore, deoxidation products are completely exposed on the surface of the molten metal and accumulated at the bottom of the metal in the REFERENCES form of a thin film by gravity. Therefore, metal and oxides are completely separated from each other [9,10] to the detection 1. K. Schwerdtfeger, C.-T. Mutale, and A. Ditze: Metall. Mater. Trans. limit, and hence, all oxygen and manganese existing in the B, 2002, vol. 33B, pp. 355-64.metal can be regarded as solute, not in the form of oxide.