LiBr-TbBr3体系相图热力学评估

采用CALPHAD技术热力学评估、计算了LiBr-TbBr3体系在整个成分范围内的平衡相图,其中组元LiBr和TbBr3的热力学性质分别采用SGTE热力学数据库和作者近期的评估结果,LiBr-TbBr3体系的热力学数据则通过对已有相图、热力学实验数据的精确评估优化获得.计算结果与实验数据的比较表明,本工作建立的热力学数据能够很好地解释现有实验结果、具有较好的物理意义.     

FeS—PbS和PbS—ZnS二元系的热力学优化

采用Ｒｅｄｌｉｃｈ－Ｋｉｓｔｅｒ多项式描述体系液相的过剩自由焓，根据试验相图和已知的热力学数据优化得到了ＦｅＳ－ＰｂＳ和ＰｂＳ－ＺｎＳ二元素的热力学参数。用优化结果计算的相图与试验测量值吻合较好。     

SmI_2－AI（A：Na，K，Rb，Cs）相图的测定和计算

用实验测定及理论计算相结合的方法构筑了ＳｍＩ＿２－ＡＩ（Ａ：Ｎａ，Ｋ，Ｒｂ，Ｃｓ）体系的相图；并通过理论计算的方法预示了一套与优化相图自治的热力学数据．     

SmI2—AI（A：Na,K,Rb,Cs）相图的测定和计算

用实验测定及理论计算相结合的方法构筑了ＳｍＩ２－ＡＩ（Ａ：Ｎａ，Ｋ，Ｒｂ，Ｃｓ）体系的相图；并通过理论计算的方法预示了一套与优化相图自洽的热力学数据。     

FeS-PbS和PbS-ZnS二元系的热力学优化

采用ＲｅｄｌｉｃｈＫｉｓｔｅｒ多项式描述体系液相的过剩自由焓,根据试验相图和已知的热力学数据优化得到了ＦｅＳＰｂＳ和ＰｂＳＺｎＳ二元系的热力学参数。用优化结果计算的相图与试验测量值吻合较好。     

MNO_3–Ca(NO_3)_2 (M=Li,Na,K)二元相图的热力学优化

基于CALPHAD方法对MNO3-Ca(NO3)2(M=Li,Na,K)二元相图的试验数据首次进行了热力学优化拟合,得到了3个二元相图的过量混合热力学性质的参数及Ca(NO3)2的熔化吉布斯自由能随温度变化的函数表达式,并用拟合的参数计算了3个二元相图,最后将计算得到的相图与试验相图进行了比较。     

有色金属合金相图的热力学分析

本文进行了合金 TD(热力学数据)和 FD 相图之间关系的简述。详细地阐述了 Le Chatelier-Schroder,van Laar—Bowen 和 Schottky 方程式在合金相图的热力学及几何热力学上的计算方法。并描述了合金中真实溶液、规则溶液的关系,以及它们的一些理论.总结了二元由 TD 确定三元 TD 的半经验公式。最后说明了用 TD 计算 FD 的方法。     

贵金属Pd-X(X=Ag,Ni,Sn)体系的相图热力学研究

对贵金属Pd-X(X=Ag,Ni,Sn)体系的相图热力学文献数据进行严格评估的基础上,采用替代溶液模型描述该3个二元系中液相和FCC＿A1相的吉布斯自由能,分别采用亚点阵模型(Pd,Sn)₁Sn₂、(Pd)_0.25(Pd,Sn)_0.75和(Pd)_0.2(Pd,Sn)_0.8描述Pd Sn₂、PdSn₃和PdSn₄相,通过CALPHAD(calculation of phasediagram)方法获得描述贵金属Pd-X (X=Ag,Ni,Sn)体系的热力学参数。相较于文献报道,本研究得到的热力学参数能更合理地描述Pd-X (X=Ag Ni,Sn)体系的实验相图数据和热力学数据,尤其在Pd-Ag相图、Pd-Ag体系和Pd-Ni体系FCC＿A1的混合焓及Pd-Sn相图富Sn端零变量反应的描述方面。计算结果与实验数据的比较表明本工作获得的热力学参数的准确性。     

Bi-Te二元体系的热力学优化

在综合评估Bi-Te体系实验数据的基础上,结合第一性原理方法计算的各中间化合物的摩尔形成焓,采用CALPHAD方法优化和计算该二元合金体系的平衡相图。液相采用置换式溶体溶液模型,对于化学计量比中间化合物Bi_7Te_3、Bi_2Te_3以及具有较大固溶度的中间相Bi_2Te、BiTe,分别采用Neumann-Kopp规则以及双亚点阵模型描述其热力学函数。通过优化,得到一组合理自洽的热力学参数,并利用该热力学参数计算相图。计算的相图与文献报道的实验信息吻合较好,计算的863 K下液相Bi的活度以及混合焓也与已有的热化学数据符合良好。     

Be-Cr二元体系热力学优化

在评估现有文献实验相图数据的基础上,采用Calphad技术优化和计算了Be-Cr二元合金体系平衡相图.液相和端际固溶体相采用替换式溶体溶液模型,化学计量比中间化合物CrBe₂和CrBe₁₂采用Neumann-Kopp规则描述它们的热力学函数.利用优化所得的热力学参数计算相图,结果能很好地解释大部分实验数据.本工作还采用Miedema模型估算了中间化合物CrBe₂和CrBe₁₂的摩尔生成焓,并与热力学计算值比较,所得结果符合良好.      

Optimization and Calculation of TbCl3-ACl（A = Li, Na, K, Rb, Cs）Phase Diagrams

Thermodynamic information of the melts involvingrare earth halides and alkali halides plays an importantrole in the preparation of rare earth metals by moltensalt electrolysis and by metallothermic reduction. Theknowledge of thermodynamics of molten s…     

Study of the liquidus and solidus surfaces of the quaternary Fe-Ni-Cu-S system: V. Refinement and addition of the data on the ternary Fe-Ni-S and Fe-Ni-Cu phase diagrams

A deep analysis and mutual fitting of the data on all ternary boundary systems have resulted in obtaining information about the phase transformations in high-sulfur Fe-Ni-S compositions and in augmentation of data on the projections of the solidus surfaces in the Fe-Ni-Cu and Fe-Ni-S systems. The studies are performed using differential thermal analysis, scanning electron microscopy, and electron-probe microanalysis. The investigation carried out is a continuation of the cycle of studies dealing with an experimental construction of the phase diagrams of the ternary systems bounding the quaternary Fe-Ni-Cu-S system.     

Thermodynamic Optimization of TmCl3-ACl （A = Na, K, Rb, Cs）Phase Diagrams

As well known, molten salt electrolysis was wide ly used for the production of rare earth metals andtheir alloys. And, phase diagrams are the most impor tant data for fused electrolytes. Dealing with the bina ry phase diagrams relating to rar…     

Experimental Investigation and Thermodynamic Modeling of the B<Subscript>2</Subscript>O<Subscript>3</Subscript>-FeO-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-Nd<Subscript>2</Subscript>O<Subscript>3</Subscript> System for Recycling of NdFeB Magnet Scrap

NdFeB magnet scrap is an alternative source of neodymium that could have a significantly lower impact on the environment than current mining and extraction processes. Neodymium can be readily oxidized in the presence of oxygen, which makes it easy to recover neodymium in oxide form. Thermochemical data and phase diagrams for neodymium oxide containing systems is, however, very limited. Thermodynamic modeling of the B₂O₃-FeO-Fe₂O₃-Nd₂O₃ system was hence performed to obtain accurate phase diagrams and thermochemical properties of the system. Key phase diagram experiments were also carried out for the FeO-Nd₂O₃ system in saturation with iron to improve the accuracy of the present modeling. The modified quasichemical model was used to describe the Gibbs energy of the liquid oxide phase. The Gibbs energy functions of the liquid phase and the solids were optimized to reproduce all available and reliable phase diagram data, and thermochemical properties of the system. Finally the optimized database was applied to calculate conditions for selective oxidation of neodymium from NdFeB magnet waste.     

Contribution of the school of V. N. Eremenko to the investigation of phase equilibrium diagrams and the thermodynamics of metallic systems

Information is given regarding the metallic systems investigated by V. N. Eremenko and his school over the decades 1960–1990. His. approach to predicting the phase equilibrium diagrams and thermodynamic properties of unknown systems, based on the generalization of experimental data obtained in this period, is discussed. The prediction level (methods of successive comparison, interpolation or extrapolation, correlation, thermodynamic modeling) depends not only on the amount and reliability of data generalized, but also on the thermodynamic properties of the systems under consideration. The necessity of using a combined approach, in which experimental and calculated phase diagram and thermodynamic data are used together, is emphasized. Mathematical optimization and evaluation of such data made it possible to obtain information on the thermodynamics and phase diagrams of previously unknown systems, and to establish a methodological base for predicting the phase diagrams of multicomponent systems of any degree of complexity.Institute of Materials Science Problems, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 9–26, July–August, 1996.     

Phase diagrams under high total gas pressures—Ellingham diagrams for hot isostatic press processes

Ellingham diagrams are very powerful phase diagrams to evaluate equilibrium phases obtained by chemical reactions. These phase diagrams were extended to higher pressures to examine stable phases under high total gas pressures. The variables under consideration consist not only of temperature and partial pressure of a gas involving the chemical reactions, but also total gas pressures. These new phase diagrams are applied to predict stable phases under hot isostatic pressing conditions (HIP phase diagram). Examples of silicon nitride sintering, and aluminium nitride sintering were given as the case of low oxygen partial pressure HIP phase diagrams. Bismuth based superconducting ceramics are discussed as an example for a high partial oxygen partial pressure HIP phase diagram. In all cases the proposed HIP phase diagrams agree well with experimental observations.     

A thermodynamic analysis and calculation of the Fe-Ni-Cr phase diagram

Phase diagrams of Fe-Ni-Cr are calculated as a function of temperature from the liquid phase down to 500 K using thermodynamic values of the pertinent phases. These phases are the liquid, fcc, bcc, sigma, and γ^′-FeNi₃ phases. Not only the thermodynamic values calculated from the models for the various phases are in agreement with experimental data available in the literature, the calculated phase diagrams are also in agreement with experimental data over a wide range of temperature. Below 1123 K, no conventional phase diagram data are available in the literature due to kinetic difficulties. However, the calculated diagram is able to explain the results obtained when the alloys are subjected to electron irradiation. Deceased, was with the Department of Metallurgical and Mineral Engineering, University of Wisconsin.