Solubility limits of selenium in copper

The solid solubility limit of selenium in copper was determined experimentally ranging from 20 ppma at 675°C to 92 parts per million atomic at 900°C. These results are extrapolated to 3 ppma at 500°C and 220 ppma at the melting point of copper using thermodynamic relationships. The enthalpy and entropy of dilute solution, ΔH _Sand ΔS _S are found to be 15.1 Kcal and 5.52 e.u. respectively. The meaning of the thermodynamic quantities ΔH _S and ΔS _S is discussed.     

Thermodynamics of rare earth metal interaction with copper

The change in thermal and thermodynamic properties along the isoformula series of rare earth metals (R) compounds with copper is analyzed. It is shown that in binary R-Cu systems the maximum thermal effects of formation are observed for the most refractory and congruently melting intermetallic compounds. In the liquid state they are observed at concentrations that are close to the composition of these compounds. It is noted that in contrast to other R scandium on reaction with copper behaves as a d-metal. __________ Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 36–43, March–April, 2006.     

Thermochemistry of liquid alloys of transition metals: I. The systems Mn-Cu and Mn-Sn

The enthalpies of mixing of solid manganese with liquid copper and liquid tin have been measured calorimetrically at 1386 K. Correcting the results by means of the known enthalpy of fusion of γ manganese at this temperature one obtains the enthalpies of mixing of undercooled liquid manganese with copper and tin. These values are compared with thermodynamic data reported in the liaterature. Formerly with The University of Chicago     

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 °C to 1110 °C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ₂) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ₂ compared with primary austenite. The volume fraction of γ₂ was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ₂ in these.     

Effect of oxygen on vacancy cluster morphology in metals

The extensive literature on oxygen chemisorption and solubility in metals is briefly reviewed, with special emphasis on the reduction of surface tension associated with oxygen adsorption. A thermodynamic model based on the adsorption equations of Gibbs and Langmuir is developed to determine the relative stability in the presence of oxygen of the void compared to the dislocation loop and stacking fault tetrahedron. Representative calculations are performed for copper, nickel, and austenitic stainless steel. Atomistic and elastic continuum calculations predict that void formation should not occur in most pure face-centered cubic metals during quenching or irradiation. However, the thermodynamic model predicts that oxygen concentrations of 30 to 1000 appm will stabilize void formation in copper, nickel, and stainless steel. Foils of copper and several Fe-Cr-Ni stainless steels containing various amounts of oxygen have been examined with electron microscopy following ion bombardment. The presence of 30 to 1000 appm O resulted in significant amounts of void formation, whereas no voids were observed in low-oxygen specimens, in agreement with the model predictions. Oxygen introduced by ion implantation was more effective in promoting void formation than residual oxygen. Solutes such as phosphorus in stainless steel reduced the effectiveness of oxygen as a void-stabilizing agent. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD     

Effect of oxygen on vacancy cluster morphology in metals

The extensive literature on oxygen chemisorption and solubility in metals is briefly reviewed, with special emphasis on the reduction of surface tension associated with oxygen adsorption. A thermodynamic model based on the adsorption equations of Gibbs and Langmuir is developed to determine the relative stability in the presence of oxygen of the void compared to the dislocation loop and stacking fault tetrahedron. Representative calculations are performed for copper, nickel, and austenitic stainless steel. Atomistic and elastic continuum calculations predict that void formation should not occur in most pure face-centered cubic metals during quenching or irradiation. However, the thermodynamic model predicts that oxygen concentrations of 30 to 1000 appm will stabilize void formation in copper, nickel, and stainless steel. Foils of copper and several Fe-Cr-Ni stainless steels containing various amounts of oxygen have been examined with electron microscopy following ion bombardment. The presence of 30 to 1000 appm O resulted in significant amounts of void formation, whereas no voids were observed in low-oxygen specimens, in agreement with the model predictions. Oxygen introduced by ion implantation was more effective in promoting void formation than residual oxygen. Solutes such as phosphorus in stainless steel reduced the effectiveness of oxygen as a void-stabilizing agent. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD     

Calorimetric research on the heat of formation of liquid alloys of copper with group IIIA and group IVA metals

Using a high-temperature isoperibolic calorimeter of our own design we have determined the concentration dependences of the enthalpy of mixing for alloys of copper with scandium, yttrium, lanthanum, titanium, zirconium, and hafnium. The directly measured enthalpies of dissolution of solid group IVA metals in liquid copper are converted into partial molar enthalpies of mixing, taking into account the data on the high-temperature component of the enthalpies and the enthalpies of fusion of the pure components. The enthalpies of mixing of the liquid alloys are given in tables and equations. The thermodynamic properties are interpreted within the framework of the theory of an ideal associative solution. Donbass State Academy of Machine-Building, Kramatorsk. Translated from Poroshkovaya Metallurgiya, Nos. 5/6(395), pp. 25–36, May–June, 1997.     

Anion-exchange separation in hydrochloric acid solutions for the ultrahigh purification of cobalt

Recent application in advanced electronics have increased the practical importance of ultrahighpurity cobalt. Anion exchange in HCl media is considered an efficient alternative to the combination of the conventional purification methods. Anion-exchange distribution functions have been determined for cobalt and the main impurity elements by the technique of batch equilibration. Spectrophotometric and elution studies confirmed the established anion-exchange behavior patterns. Based on the new and the available distribution functions, combined with the assessment of thermodynamic stability, a procedure of anion-exchange separation has been devised to eliminate virtually all the impurities from the cobalt-chloride solution. The major shortcoming of previously proposed anion-exchange procedures—failing to separate copper sufficiently—has been corrected by the introduction of a preliminary step under reduced conditions, removing copper from the solution by sorption in the monovalent state. The rest of the impurities are eliminated in a second anion-exchange step by applying rinsing and elution stages under oxidizing conditions. The optimum parameters of the procedure have been determined according to performance characteristics (purification ratios, yields, and volume efficiencies) derived from the analysis of elution curves obtained with laboratory-scale ion-exchange columns. Special computer programs have been developed to facilitate thermodynamic simulation, analytical correction, and data processing.     

The thermodynamic activities of copper and iron in the system copper-iron-platinum at 1300°C

The vapor pressure of pure liquid copper and the partial pressures of copper exerted by six alloys in the system Cu−Fe, 12 alloys in the system Cu−Pt, and 44 alloys in the system Cu−Fe−Pt in the temperature range 1240°C to 1360°C have been measured by the Knudsen effusion technique, and the thermodynamic properties of the systems at 1300°C have been calculated from the vapor pressures. The system Cu−Fe shows large positive deviations from Raoultian ideality, and the system Cu−Pt shows large negative deviations. The activities of Fe in solid solutions in the system Cu−Fe−Pt at 1300°C have been calculated by Gibbs-Duhem integration of the activities of Cu. This paper is based on a presentation made in the T.B. King Memorial Symposium on “Physical Chemistry in Metals Processing” presented at the Annual Meeting of The Metallurgical Society, Denver, CO, February, 1987, under the auspices of the Physical Chemistry Committee and the PTD/ISS.     

Characterization of the nucleation and growth behavior of copper precipitates in low-carbon steels

The nucleation and growth behavior of copper precipitates in ferrite was investigated both theoretically and experimentally for two low-carbon steels with and without niobium additions in samples cooled directly to the desired aging temperature from the austenitizing temperature. Theoretical nucleation and growth rate models were constructed using calculated thermodynamic data in conjunction with classical theories. The maximum nucleation and growth rates for Cu were experimentally determined to be 8.0 × 10²¹ nuclei/m³ s at 612 °C and 0.12 nm/s at 682 °C, respectively. Using an experimentally determined “effective” activation energy for the diffusion of copper, the theoretical nucleation rate curve compared very well with the hardness data for the first 5 minutes of aging. The growth behavior of the Cu precipitates was investigated through use of a conventional transmission electron microscope (TEM) for samples directly aged at 550 °C. For aging times up to 21 hours, the average precipitate size scaled with a time dependence of t ^1/2.     

Phase equilibria in Cu-As(Sb,Bi)-O systems under conditions of the existence of a copper-based alloy

Solubility surfaces of components in metal melts for the Cu-As-O, Cu-Sb-O, and Cu-Bi-O systems in the range t = 1100–1300°C and high-temperature fragments of phase diagrams of oxide systems Cu₂O-R₂O₃ (R is As, Sb, Bi) are constructed based on thermodynamic calculations. Phase equilibria in the Cu-Sb-O and Cu-Bi-O systems are investigated experimentally. The results can be used to analyze the production processes of copper and copper-based alloys.     

Enthalpies of formation of liquid binary (copper + iron, cobalt, and nickel) alloys

The enthalpies of formation of liquid binary (Cu+Fe, Co, Ni) alloys are studied by direct reaction calorimetry in the whole range of compositions at 1873, 1823, and 1753 K, respectively. The integral molar enthalpies of mixing are found to be positive in all three systems with the maximum values approaching 10.8±0.7 kJ/mol⁻¹ at x _Fe=0.43, 7.1±0.9 kJ/mol⁻¹ at x _Co=0.55, and 3.7±0.5 kJ/mol⁻¹ at x _N1=0.53. Partial molar enthalpies at infinite dilution constitute 59.4±3.3 kJ/mol⁻¹ for iron, 44.3±4.1 kJ/mol⁻¹ for cobalt, and 14.9±2.2 kJ/mol⁻¹ for nickel in liquid copper. Similar values for copper in liquid iron, cobalt, and nickel are 36.6±3.9, 45.3±6.0, and 17.7±4.4 kJ/mol⁻¹, respectively. The results are compared with the thermodynamic data available in literature and discussed in connection to the equilibrium-phase diagrams. In particular, decreasing from Cu-Fe to Cu-Ni liquid alloys positive values of the excess thermodynamic functions of mixing are fully in accord with the growing stability of phases in these systems. The excess entropies of mixing are estimated by combining the established enthalpies with carefully selected literature data for the excess Gibbs functions. Analysis of possible contributions to the enthalpies of mixing indicates that the experimentally established regularity in ΔH values along the 3d series is likely to arise from the difference in d-band width and d-electron binding energy of the alloy constituents.     

Cohesive energy, properties, and formation energy of transition metal alloys

The cohesive energy of transition metals and its contributions related to the s-and d-electrons are calculated. The correlation of interatomic bonding strength, molar volume, and compressibility of transition metals with cohesion energy and corresponding contributions to it is shown. It is demonstrated that the s-electrons play an important part in the cohesion of transition metals. The main contributions to the formation energy of disordered alloys of copper with transition metals are calculated using the tight-binding approach. The results obtained are in qualitative agreement with experimental data on the thermodynamic properties of Cu-3d-metal systems. __________ Translated from Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 37–54, 2008.     

Thermodynamic behavior of bismuth in copper pyrometallurgy: Molten matte,white metal and blister copper phases

This study developed thermodynamic data relating to the behavior of bismuth in copper smelting, converting and refining processes. The activity of bismuth was set by establishing a known vapor pressure of bismuth over melts of various phases. The melts were equilibrated with the vapor, and the resulting bismuth content used to establish bismuth activity coefficients. Experiments were carried out, under controlled oxygen potentials, at 1200 and 1250 °C. Results show that bismuth deviates positively from Raoult's Law at both 1200 and 1250 °C in copper (γ_Bi = 2.17, 2.27), white metal (γ_Bi = 6.1, 6.1), Cu₂S with 2 wt pct FeS (γ_Bi = 8.0, 8.0), Cu₂S with 4 to 6 wt pct FeS (γ_Bii = 16.4, 16.4) and Cu2S with 8 to 70 wt pct FeS (γ_Bi = 13.6, 13.6), respectively. Sabri Arac formerly Research Assistant at University of Arizona Gordon H. Geiger formerly head of the Department of Metallurgical Engineering at the University of Arizona     

A thermodynamic study of digenite solid solution (Cu2-δS) at 600 to 1000°C and a statistical thermodynamic critique on general nonstoichiometry

A very accurate experimental method to determine the composition of metal-saturated sulfides has been developed and applied to Cu_2-δS. The technique consists of using a high-sensitivity thermobalance which operates in a controlled atmosphere of H₂-H₂S gas. By this method it was shown that Cu-saturated Cu_xS is stoichiometric(x= 2.0000 ± 0.0002) between 700 and 1000°C. The free energy of formation for Cu₂S was found to be: 2Cu(s) + 1/2 S₂(g) = Cu_2.0000S(s), ΔG⁰ = -30,610 + 6.80T (cal/mole). The sulfur partial pressure was determined over nonstoichiometric Cu_2-δS for sulfur contents up to 21 pct. From the result, thermodynamic functions such as activity of copper, heats and entropies of solution were calculated as a function of nonstoichiometric composition. It was thermo-dynamically demonstrated that previous models dealing with nonstoichiometric oxides (or sulfides) based on the law of mass action,i.e., δ = const ie 67 01 (or ie 67 02), are inconsis-tent as they fail to satisfy the Gibbs-Duhem relation and also fail to account for the dis-sociation pressure over the stoichiometric composition. To resolve this dilemma, a sta-tistical thermodynamic method of constructing the grand partition function was introduced. Stoichiometry and nonstoichiometry of the Cu_2-δS were then explained by postulating an ionic crystal consisting of Cu⁺, Cu²⁺, Cu⁰ and neutral vacancies in the copper sublattice and S²⁻ and neutral vacancies in the sulfur sublattice. Formerly Postdoctorate Fellow, National Research Council of Canada, Ottawa, Ontario     

Thermodynamics and phase relationships of transition metal-sulfur systems: Part III. Thermodynamic properties of the Fe-S liquid phase and the calculation of the Fe-S phase diagram

An associated solution model is applied to describe the thermodynamic behavior of Fe-S liquid. This model assumes the existence of ‘FeS’ species in addition to Fe and S in the liquid. With two solution parameters for each of the binaries Fe-‘FeS’ and ‘FeS’-S, this model accounts for the compositional dependence of the thermodynamic properties of Fe-S liquid from pure Fe to pure S over a wide range of temperature. The binary Fe-S does not contribute significantly to the excess Gibbs energy of the liquid due to the rather small dissociation constant of ‘FeS’ to Fe and S. Using this model for the liquid phase and a defect thermodynamic model for the pyrrhotite phase, the Fe-S phase diagram is calculated. The calculated diagram is in excellent agreement with the experimental data, accounting for the range of homogeneity of pyrrhotite at all temperatures. Both the thermodynamic and phase diagram data are obtained from the literature. Formerly Post-Doctoral Research Associate, Materials Department, College of Engineering and Applied Science, University of Wisconsin-Milwaukee.     

Thermodynamic modeling of lead distribution among matte, slag, and liquid copper

Recently, a thermodynamic database was developed for the calculation of equilibria involved in the production of copper. The present study is concerned with the further development of the thermodynamic models and the database of model parameters for the matte, slag, and blister copper phases with a view to including Pb in the database and permitting calculations in the seven-component system Pb-Cu-Ca-Fe-Si-O-S. Thermodynamic and phase equilibrium data available in the literature are reviewed, critically assessed, and optimized with the modified quasi-chemical model. When used with the Gibbs energy minimization software and other databases of the FACT thermodynamic computing system, the database developed in the present study can be used for the calculation of matte-slag-copper-gas phase equilibria during copper smelting and converting. The distribution of lead among these phases can be computed. For example, the distribution of lead among matte, silica-saturated slag, and copper has been calculated at metal saturation, or under fixed partial pressure of SO₂, and has been compared with the available experimental data. The Pb distributions among the equilibrium phases have been calculated under various conditions, which are difficult to study experimentally, such as at magnetite saturation or under various oxygen partial pressures and iron to silica ratios in the slag.     

金川镍阳极液硫化除铜的研究

结合已有的热力学数据,对采用硫化法镍阳极液中除铜过程进行了热力学平衡计算,计算了除铜终点各离子的平衡浓度,绘制出了298.15 K时体系中除铜终点logcMe-logcS图和c-pH图。计算表明,采用硫化法可以成功将镍阳极液中铜和部分铅、锌除去。对所绘的热力学平衡图分析表明,随着总硫浓度的增加,铜、铅、锌、镍依次沉淀;在酸性条件下,改变pH对除铜深度影响不大,但控制适当的pH有利于得到铜镍比较高的渣;此外,适当增加镍电解液中铜含量、降低镍电解液中镍含量有利于提高渣中的铜镍比。除铜实验表明,采用硫化法除铜可以得到含铜0.40 mg/L、铅3.94 mg/L、锌1.61 mg/L的除铜后液。     

A thermodynamic analysis of the Pb−S system and calculation of the Pb−S phase digram

An associated solution model is used to describe the thermodynamic properties of the liquid phase in the Pb−S system, where the existence of ‘PbS’ species is assumed in addition to ‘Pb’ and ‘S’. The liquid is now considered as a pseudo-ternary solution of ‘Pb’, ‘S’, and ‘PbS’ in which the concentrations of the species are related by an equilibrium constant. The thermodynamic properties of the intermediate phase, PbS, are described by a point-defect model. The doubly ionized vacancies on the Pb and the S sites are considered to be the dominant defects and the nonstoichiometry is caused by the excess of vacancies on either site. The parameters of these models are obtained by simultaneous optimization of the available thermodynamic and phase equilibria data. The Pb−S phase diagram is then calculated, using these thermodynamic models, and compared with the experimental data.     

A thermodynamic analysis of the copper-sulfur system

An associated solution model is applied to describe the thermodynamic behavior of Cu-S liquid. This model assumes the existence of ‘Cu₂S’ species in addition to Cu and S in the liquid. With two solution parameters for each of the binaries Cu-‘Cu₂S’ and ‘Cu₂S’-S, this model accounts for the compositional dependence of the thermodynamic properties of Cu-S liquid from pure Cu to pure S over a wide range of temperature. The binary Cu-S does not contribute significantly to the excess Gibbs energy of the liquid due to the rather small dissociation constant of ‘Cu₂S’ to Cu and S. Using this model for the liquid phase, a statistical thermodynamic model for the digenite phase, and appropriate thermodynamic equations for the other phases, the Cu-S phase diagram is calculated. The calculated diagram is in excellent agreement with the experimental data, accounting for the range of homogeneity of digenite at all temperatures. Formerly with the Materials Department, University of Wisconsin-Milwaukee Formerly Professor of Materials Engineering and Associate Dean for Research of the Graduate School of the University of Wisconsin-Milwaukee.