Thermodynamic properties of Ni-S melts between 700° and 1100°c

The vapor pressure of sulfur over Ni-S melts of various compositions was calculated from the equilibrium weight of the melt in gas streams of known H₂S-H₂ composition. The Gibbs-Duhem equation was used to calculate the activity of nickel and other thermodynamic properties. For the reaction: 3Ni(S) + S₂(g) ⇌ Ni₃S₂(l) the suggested free energy rslationship is: ΔG° = -57,910 + 15.89T (800° to 1100°C). The Calculations were extrapolated to predict that for the reaction: Ni(s) + 1/2S₂(g) ⇌ NiS(l), ΔG° = -26.730 + 10.5T (1000° to 1100°C)     

Thermodynamic behaviour of phosphorus in Mn-Si-Ca-P melts

Thermodynamic experiments of Mn-Si-Ca-P melts were carried out in Mo-wire-heated furnace. With these experimental data, the first and second order activity interaction coefficients of Ca, Si and P upon P under the conditions of the same activity and the same concentration method were evaluated. The standard free energy of solution of P in liquid Mn based on 1 wt.% solution standard formulated in temperature was given and it only holds near 1623 K.     

Characterization of the damping properties of die-cast zinc-aluminum alloys

Characterization of the mechanical damping properties of a series of die-cast zinc-aluminum alloys is described. Over the range of variables (temperature, frequency, and vibration strain amplitude) normally encountered in service applications, it is shown that the damping consists of two components. Both components are due to linear relaxation mechanisms: the first is a thermoelastic relaxation and the second is the low-temperature tail of a broadened boundary relaxation. Some of the alloys exhibit elevated damping levels over a useful frequency range, particularly at the temperatures encountered in under-hood applications in automobiles. This paper is based on a presentation made in the symposium “Acoustic/Vibration Damping Materials” presented during the TMS Fall Meeting, Indianapolis, IN, October 1–5, 1989, under the auspices of the TMS Physical Metallurgy Committee.     

基于原子-分子理论的二元合金熔体热力学计算

分别使用Miedema、MIVM、NRTL、Wilson二元合金系热力学模型及FactSage热力学软件计算Bi-Pb、Bi-Sn、Cd-Pb、Pb-Sn 4个二元合金系的活度值,并与实验值进行比较.结果表明:Miedema、MIVM、NRTL、Wilson模型计算不同体系活度的效果不同,每种模型都有其适用的体系.而FactSage热力学软件计算的活度均与实验值吻合较好,文中使用FactSage分别计算Bi-Pb、Bi-Sn、Cd-Pb、Pb-Sn 4个二元系不同温度下的活度值.同时利用原子-分子理论计算Bi-Pb二元系质量作用浓度,给出生成金属间化合物BiPb反应的标准吉布斯自由能的表达式.      

Al-Si-Fe合金熔体质量作用浓度的热力学模型

基于原子分子共存理论(AMCT)建立了计算Al-Si二元熔体及Al-Si-Fe三元熔体结构单元质量作用浓度的热力学模型.针对Al-Si二元系熔体,根据FactSage热力学软件计算的活度得到生成复杂分子Al2Si和AlSi的反应的标准摩尔吉布斯自由能的表达式,进而获得了 Al-Si二元熔体中标准摩尔溶解吉布斯能变的表达...     

Thermodynamic modeling of the reaction of lanthanum with components of iron-based melts

Thermodynamic analysis of binary and ternary oxide systems containing the oxide La₂O₃ permits the formulation of a database of energy parameters in the theory of subregular solutions for oxide melts adjacent to the region of existence of metallic melts in the phase diagram of the system. The temperature dependence of the equilibrium constants for the heterogeneous reduction of steel is established. The solubility surfaces of components in oxygen-bearing steel are plotted for the Fe–Al–La–O–C, Fe–Ca–La–O–C, Fe–Mg–La–O–C, Fe–Si–La–O–C, and Fe–Cr–La–O–C systems. Diagrams are plotted for the complex reduction of steel by alloys and mixtures containing active and alloying elements: Ca, Mg, Si, Al, Cr, and La. Analysis is undertaken for thoroughly reduced and sulfur-free steel. With the usual reduction system, in which rare-earth metals are added to the steel after the introduction of calcium, silicon, and aluminum, the inclusions that form—consisting of a conglomerate of calcium and magnesium aluminates—provide the substrate for the deposition of small fractions, actively interact with the liquid component of the inclusions, and dissolve in the liquid component. Therefore, La₂O₃ is not present as an independent phase in the metallic inclusions.     

Dynamic properties of Aluminum-Lithium and Aluminum-Magnesium melts

A comparison of calculated concentration dependences of the electrical resistivities of the Al-Li and Al-Mg systems suggests that a metal-nonmetal phase transition takes place in the Al-Li system. This assumption casts some doubt on the mechanism of quasi-chemical electron localization used to explain the metal-nonmetal phase transition in Pb-Li and Sn-Li melts.     

Dynamic and kinetic properties of Al-Li melts

The dynamic and kinetic properties of Al-Li melts are calculated. The liquid phase of this system is shown to be characterized by three states with different ion distributions and different degrees of electron localization.     

Thermodynamic modeling of the interaction of Y2O3 with Nb-Si-based melts

Thermodynamic modeling of the interaction of the yttrium ceramics with Nb-Si-based melts alloyed with Ti, Cr, Hf, and Al is performed. It is shown that the result of their chemical interaction is the formation of a solid solution of hafnium oxide (HfO₂), while other elements almost do not participate in the interaction. It is revealed in the course of modeling that the main interaction mechanism is the reduction of yttrium oxide upon its dissolution from ceramics into the metallic solution, in which the Y content depends on the temperature, composition, and amount of the metallic phase.     

Thermodynamic properties of condensed silicides

An approximate generalized equation is obtained for the temperature dependence of the change in Gibbs energy in the atomization of condensed silicides; this equation takes account of the number of atoms present in the silicides and their calculated boiling points. For the 16 silicides considered, the discrepancy between the maximum calculated value and the mean is no more than 10%. On that basis, the proposed method may be used to verify data from other sources and also for approximate prediction of the thermodynamic properties of silicides that have not yet been studied.     

Thermodynamic properties of yttrium gernianwes

We have determined the Gibbs free energy, enthalpy, and entropy of formation for yttrium germanides by measuring the emf of high-temperature galvanic cells at 820–920 KInstitute of Materials Science, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5–6, pp. 103–107, May-June, 1996. Original article submitted July 13, 1994.     

Thermodynamic properties of chromium antimonides

Conclusions A method involving measuring the emf's of the electrolytic cells (–) Cr_s ¦KCl-NaCl-LiCl+CrCl₂¦[Cr-Sb]_s (+) was used to determine some thermodynamic characteristics (isobaric-isothermal potentials, heats, and entropies of formation) of the chromium antimonides CrSb and CrSb₂.Translated from Poroshkovaya Metallurgiya, No. 4 (124), pp. 55–58, April, 1973.     

Thermodynamic properties of chromium silicides

Conclusions The method of measuring the emf's of high-temperature galvanic cells was employed for determining the isobaric-isothermal potentials, entropies, and heats of formation of the chromium silicides CrSi₂, CrSi, Cr₅Si₃, and Cr₃Si in the temperature range 700–850°C. Using literature data upon the enthalpies and entropies of the chromium silicides and pure chromium and silicon, the standard heats and entropies of formation of these silicides were calculated.Translated from Poroshkovaya Metallurgiya, No. 7 (115), pp. 61–65, July, 1972.