Liquidus Temperatures of Cryolite Melts With Low Cryolite Ratio

The effect of calcium fluoride on liquidus temperatures of the cryolite melts with a low cryolite ratio (CR) was studied. The systems KF-NaF-AlF₃ and KF-LiF-AlF₃ with CRs of 1.3, 1.5, and 1.7 have been investigated. The liquidus curves of systems containing CaF₂ are different and depend on the K/(K + Na) and K/(K + Li) ratios. In potassium cryolite with CRs of 1.3 and 1.5, the calcium fluoride solubility is low and increases with NaF (LiF) concentration.     

钢的液相线温度的计算

基于最新的Fe-i二元相图,系统计算了铁基合金中20种常见合金元素（含量为0％－21％）对纯铁熔点的影响值,据此给出了新的钢的液相线温度计算模型及组元的温度系数,并以齿轮钢为例进行了验证。结果表明,液相线温度的计算精度进一步提高。     

Differential Calculation Model for Liquidus Temperature of Steel

The liquidus temperature of steel is greatly affected by its chemical composition; therefore, the value of the liquidus temperature can vary among different types of steel. In this study, on the basis of the concept of differentiation, the Fe‐i binary phase diagram is analyzed using Photoshop image processing software. The effects of eleven common alloying elements (C, Si, Mn, P, S, Ca, Ni, Cu, Cr, Nb, and Mo, whose content is between 0%～4%) on the melting point of pure iron are analyzed. This analysis proves the following assumption to be incorrect: the relationship between the change in liquidus temperature and the content of element i is a linear relationship; this assumption is the basis of traditional liquidus calculation models. A new model for calculating the liquidus temperature of steel is established in this study. As compared to data from other literature, the model proposed in this paper has good generality and the calculation error of the liquidus temperature of steel is between ?3 and 4 °C, which is acceptable. A statistical analysis of the experimental data for different steel grades (obtained from Laiwu Special Steel) using the developed model showed that 87.2% of the absolute deviation values of the temperature are within 4 °C. This result shows the model to be both reasonable and credible.     

钙元素对钢液相线温度的影响

用差热分析法(DTA)测定了含0.000 9%~0.003 0%Ca的0.14%~0.76%C-0.48%~1.48%Mn钢及不含Ca的0.15%~0.63%C-0.56%~1.32%Mn钢的液相线温度。通过比较分析测定值和计算值,得到钙元素对钢液相线温度的影响系数A值的平均数为-0.142 5,并对传统液相线温度计算公式进行了修正,提高钙处理钢水浇铸时过热度控制的精度。     

铝电解质初晶温度检测及其数模拟合的研究

直接测定了铝电解质实际样品的初晶温度。根据分析结果拟合出该体系初晶温度与分子比数学模型。试验了不同材质的高温传感器及保护套管 ,石墨坩埚作盛样器 ,对其测温的准确度作了验证 ,并对其形状作了改进 ,使传感器的使用寿命得到了延长。     

Study on Liquidus Temperature of NaF-KF-LiF-AlF3 System with Low Cryolite Ratio

Metallurgical and Materials Transactions B - Development of an energy-efficient method for aluminum manufacturing is the current research trend in the aluminum electrolysis industry. A...     

Ti-TiNi-HfNi-Hf Liquidus surface

Physical and chemical analysis methods are used for the first time to examine the Ti-TiNi-HfNi-Hf alloys in the melting-crystallization region. The liquidus surface is shown to consist of six fields of primary phase crystallization: λ₁, η, δ, θ, β, and α. The largest fields are of δ-and β-phases. The λ₁ ternary phase is formed by peritectic reaction l + δ → λ₁. There are five invariant equilibria involving liquid on the Ti-TiNi-HfNi-Hf solidus surface. The liquidus surface, vertical sections, and alloy crystallization scheme are constructed.     

高温熔盐初晶温度和分子比槽前分析仪的研制

对电解铝厂实际电解质初晶温度的直接测定进行了研究,模拟出初晶温度与电解质组分以及初晶温度与分子比之间的关系模型,并利用计算机进行处理。通过测定电解质初晶温度及时给出各组分含量、分子比,研制出一种便携式初晶温度、分子比槽前分析仪。该仪器可用于电解铝厂电解质温度及分子比的现场分析。     

Liquidus temperatures in the Ti-Al system

Liquidus temperatures were determined for the titanium-aluminum system at compositions ranging from 41 to 62 at. pct Al. The measurements were obtained by inducing solidification of slightly undercooled melts under containerless processing conditions using electromagnetic levitation. Absolute temperatures were determined by optical pyrometry in combination with independent measurements of spectral emissivities by laser polarimetry. The present liquidus temperatures are in agreement with two sets of literature values and are consistent with a set of solid-state literature data. These values exceed those selected in one recent proposed phase diagram revision by about 30 K and are as much as 40 to 60 K higher than those in another proposed revision. Formerly Ph.D. Candidate, Department of Materials Science and Engineering, Vanderbilt University     

Liquidus of Silicon Binary Systems

Thermodynamic knowledge about liquid silicon is crucial for the production of solar-grade silicon feedstock from molten silicon. In the current study, liquidus for silicon binary alloys is formulated using a previously developed method in which the liquidus curve is calculated using two constants. The liquidus measurements for the silicon portion of the silicon alloys with Al, Ca, Mg, Fe, Ti, Zn, Cu, Ag, Au, Pt, Sn, Pb, Bi, Sb, Ga, In, Ni, Pd, Mn, and Rh are reviewed, and the consistent data were used to determine the liquidus constants. The liquidus curves for silicon binary systems are calculated and plotted. It is indicated that the calculated liquidus curves fit well with the experimental data. A correlation between the determined liquidus constants is also observed, which can be used to gain a better understanding of the thermodynamics of the silicon binary melts.     

Liquidus Projection of the Ag-Sn-Te Ternary System

The Ag-Sn-Te ternary system is of interest to thermoelectric applications and its liquidus projection is determined in this study. Forty Ag-Sn-Te ternary alloys are prepared and their primary solidification phases are determined. These different primary solidification phase regions include three terminal solid solutions: Ag, Sn, and Te; six binary intermediate phases: SnTe, β-Ag₅Te₃, Ag_1.9Te, Ag₂Te (assuming no phase transformation), ζ-Ag₄Sn, and ε-Ag₃Sn; and one ternary compound, AgSnTe₂. These data, together with the phase diagrams of the three constituent binary systems, are employed to construct the univariant lines of the liquidus projection. The temperature-descending directions of these univariant lines are determined using thermal analysis results and mass balance concept. The types of invariant reactions and the reaction temperatures are determined from the temperature-descending directions of the univariant lines and by thermal analysis. There are two Class I reactions, five Class II reactions, and one Class III reaction. The invariant reaction with the highest reaction temperature is L + Ag = Ag₂Te + ε-Ag₃Sn, at 992.7 ± 4 K (719.5 ± 4 °C), and that with the lowest reaction temperature is L = Sn + ε-Ag₃Sn + SnTe, at 494.2 ± 4 K (221 ± 2 °C).     

Liquidus temperature determination in multicomponent alloys by thermal analysis

Thermal analysis is often used to determine equilibrium phase boundary temperatures such as the liquids. Accurate measurements require proper calibration procedures, which are standard for given instruments. In multicomponent alloys such as RENE N5 and PWA 1484 superalloys, a complex melting behavior associated with the solidification structure was exposed by examining the melting response at different heating rates. The observed variability in the melting signal is related to the sample processing history and is not addressed by the various standard calibration methods or supplemental procedures for different heating rates. The liquidus temperature can be determined under conditions approaching full compositional equilibrium by the application of an interrupted-heating thermal analysis protocol. The approach provides a new strategy for the reliable determination of phase boundary temperatures by thermal analysis.     

Liquidus surface of the Mg-Sm-Tb phase diagram

Differential thermal, electron microprobe, and X-ray diffraction analyses and metallography are used to study Mg-Sm-Tb alloys containing up to 30% Sm or Tb. Polythermal sections and the solidification surface of the Mg-Sm-Tb phase diagram are constructed for the Mg-rich region. In the composition range under study, nonvariant transition-type equilibrium L + Mg₂₄Tb₅ = (Mg) + Mg₄₁Sm₅ is found to exist at a temperature of 539°C.     

Thermodynamics of Mn in Cu-Mn Melts

The present work aimed to measure the thermodynamic data of manganese in Cu-Mn melts over a broad manganese concentration range, using the equilibrium among the liquid copper/MnO_(s)/CO-CO₂ gas mixture in the temperature range from 1673 K to 1873 K (1400 °C to 1600 °C). Darken’s quadratic formalism was introduced to correlate the activity coefficient of manganese in copper to composition, and the excess molar Gibbs energy change of mixing of Cu-Mn melts was described satisfactorily by Redlich–Kister type polynomial.     

Solubility of Aluminum in Cryolite-Based Melts

The solubility of aluminum in NaF-AlF₃-Al₂O₃ melts was investigated between 800 °C and 960 °C. The amount of dissolved metal in rapidly cooled samples was analyzed by the reaction with hydrochloric acid under the formation of hydrogen—the volume of which then was determined. Four thermodynamic models that describe the high-temperature equilibrium of aluminum reactions with the NaF-AlF₃ melt were proposed. The best fit for the experimental data was obtained by assuming the existence of a monovalent aluminum species, AlF and $ {\text{AlF}}_{ 2}^{ - } , $ as well as elemental sodium.     

Diffusion of Silicophosphate Melts

In order to investigate the mechanism of diffusion in silico-phosphate melts, measurements were carried out in Pt-10 pet Rh capillaries. The melts in the capillaries were quenched and the resulting glasses examined using paper chromatography. From the diffusion rates and the structure of the glasses, it is concluded that the silicons can move from the center of one phosphate chain to another without difficulty.     

Liquidus temperatures in calcium ferrite slags in equilibrium with molten copper

Experimental laboratory methods have been developed that enable phase-equilibria studies to be carried out on slags in the system Ca-Cu-Fe-O in equilibrium with metallic copper. These techniques involve equilibration at temperature, rapid quenching, and chemical analysis of the phases using electron-probe X-ray microanalysis (EPMA). Equilibration experiments have been carried out in the temperature range of 1150 °C to 1250 °C (1423 to 1523 K) and in the composition range of 4 to 80 wt pct “Cu₂O,” 0 to 25 wt pct CaO, and 20 to 75 wt pct “Fe₂O₃” in equilibrium with metallic copper. Liquidus and solidus data are reported for the primary-phase fields of spinel (magnetite) and dicalcium ferrite. The resulting data have been used to construct liquidus isotherms of the CaO-“Cu₂O”-“Fe₂O₃” system at metallic copper saturation.