Enthalpy of formation and excess entropy for dilute copper-based alloys: Experimental and theoretical study

Gachon, J.C.; Notin, M.; Cunat, Christian; Hertz, J.; Parlebas, J.C.; Moraitis, George; Stupfel, B; Gautier, François

doi:10.1016/0001-6160(80)90139-x

Cited by 25 publications

(17 citation statements)

References 18 publications

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“…Using the emf method with a solid electrolyte authors of [27] established the value for thermodynamic activity of BCC-chromium in a solid solution based on copper: a Cr = 0.15 for alloy with x Cr = 0.001 at 1300 K. It is the only experimental result obtained for equilibrium solid solutions of the system at present. A regularity parameter for the FCC-solution was calculated on its base in [27]. It constituted 43.1 kJ/mole.…”

Section: Thermodynamic Properties Of Phasesmentioning

confidence: 99%

“…Model parameters were optimized using a Thermo-Calc program. In the first stage of thermodynamic optimization data on the thermodynamic properties of the liquid phase [10,11,16,25,26], for the FCC-solution [27], and available information for the parameters of eutectic transformation [1, 2, 4-7, 9, 12, 13] were used. In the second stage of optimization experimental data on the position of the liquidus line of the (Cu)-phase [6] and (Cr)-phase [9,[11][12][13] for copper-rich alloys, and also data on the position of the solidus line of the (Cr)-phase [9,12] and the saturation limits of the (Cu)-phase [4][5][6][7][8] were included.…”

Section: Thermodynamic Assessment Of the System And The Modelmentioning

confidence: 99%

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Phase equilibria and thermodynamics of binary copper systems with 3d-metals. III. Copper-chromium system

Турчанин

2006

Powder Metall Met Ceram

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Experimental information on phase equilibria and thermodynamic properties of the Cu − Cr system are described within the framework of the CALPHAD-method in order to obtain self-consistent analytical description of the system. The resulting set of coefficients makes it possible to calculate the thermodynamic properties of phases and related equilibrium transformations. A model of Gibbs excess free energy of the liquid phase takes into account excess heat capacity. Possible metastable transformations in the system, such as the immiscibility of supercooled liquid alloys and formation of supersaturated terminal solid solutions, are discussed.Keywords: phase equilibrium diagram, thermodynamics, thermodynamic modelling, metastable transformations, copper alloys, supersaturated solid solutions, immiscibility of supercooled melts.Alloys of copper and chromium have found extensive application in modern industry as heat-resistant materials that exhibit high electrical and thermal conductivity. This has governed their use for the preparation of currentconducting parts of mechanisms operating under significant mechanical and thermal loads (crystallizers of furnaces, first of all), special electrodes, and also in order to prepare electrical contact materials. An even more promising use of two-component alloys of copper and chromium opens up in view of the possibility to increase their mutual solubility with help of modern, highly nonequilibrium methods of metallurgical synthesis, such as melt quenching, mechanical alloying, and deposition from the gas phase.A solution of important technological problems, such as preparation of materials with an extended concentration range of solid solutions, development of their heat treatment conditions in order to provide the required complex of operating properties, demands an exact idea about the nature of equilibrium and nonequilibrium transformations in the system. The least studied among them remained the high-temperature part of the phase diagram and closely connected with it question of the possibility of liquid phase separation. When modern experimental methods cannot give a clear answer at this question, an attempt to solve it in the context of constructing a thermodynamic model of the system is of an undoubted interest. PHASE EQUILIBRIAStable phase transformations. Phase equilibria in the system have been studied in a number of works [1][2][3][4][5][6][7][8][9][10][11][12][13]. It has been established that the copper − chromium system is of the eutectic type. There are two regions of primary solidification with insignificant concentration ranges of its existence on the phase diagram (Fig. 1): a FCC-solution based on copper, i.e. (Cu)-phase, and a BCC-solution based on chromium, i.e. (Cr)-phase. The peculiarity of the phase diagram is an almost horizontal part of the (Cr)-phase liquidus line. Most often questions discussed concerning the nature of phase equilibria in the system are the probability of the occurrence of separation in the liquid phase, the stable or metastable nature...

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Section: Thermodynamic Properties Of Phasesmentioning

confidence: 99%

Section: Thermodynamic Assessment Of the System And The Modelmentioning

confidence: 99%

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. III. Copper-chromium system

Турчанин

2006

Powder Metall Met Ceram

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“…The first mixing enthalpy of fcc-cobalt and solid copper was established in [24] by calorimetry of an alloy with x Co = 0.02 dissolved in tin. Seven tests resulted in 73 ± 21 kJ/mole.…”

Section: Thermodynamic Properties Of Solid Alloysmentioning

confidence: 99%

“…First, we used data on the mixing enthalpies of liquid alloys [16][17][18], activities of melt components [15,20,22] and solid solutions [23][24][25], and the coordinates of the peritectic reaction [27]. The next step took into account the positions of the liquidus line [22,27,28,30,34], the solidus line of the (Cu)-phase [13,29,31,32] and (αCo)-phase [13,32,33,35], as well as the boundaries of the miscibility gap of the supercooled liquid phase [30,34,[37][38][39][40].…”

Section: Thermodynamic Assessment Of the System And The Modelmentioning

confidence: 99%

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. V. Copper-cobalt system

Турчанин

Agraval

2007

Powder Metall Met Ceram

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669.35:536.717 The mixing enthalpies and activities of components in liquid and solid alloys as well as the parameters of stable and metastable transformations are used for the thermodynamic evaluation of the Cu − Co system within the CALPHAD approach. The thermodynamic parameter for the (εCo) phase is evaluated within the Miedema model. The thermodynamic model of the system provides a self-consistent description of all thermodynamic quantities and phase transformations, including metastable ones. The description is in close agreement with experimental data. The thermodynamic model of system is used to explain the extension of the concentration range of supersaturated fcc solutions prepared by melt quenching.Copper and cobalt alloys are of practical importance and great interest for developing the theory of transitionmetal solutions.Binary alloys and more complex compositions based on the Cu -Co system are used to produce materials with high electrical and thermal conductivity combined with low thermal expansion [1]. Supersaturated solid solutions with unique electric and magnetic properties based on the system phases result from melt quenching [2], vapor deposition [3, 4], electric deposition [5], and mechanical alloying [6]. The magnetic properties of these solutions over a wide temperature range demonstrate the qualities of paramagnetics, ferromagnetics, and spin glass [7]. In quenching, the (εCo)-phase undergoes martensitic transition [8,9], which stabilizes with increasing copper content [10]. Nanocrystalline materials with unique mechanical properties were produced from a copper-based solid solution [11].The thermodynamic properties of the system phases and phase equilibria are of definite interest for metallurgy theory; in particular, for the theory of copper -nickel -cobalt pyrometallurgy and cobalt regeneration from secondary raw materials.The system is fundamentally interesting as its two metals, which have similar fcc structures, demonstrate a substantial concentration region of solid immiscibility, complete liquid miscibility, and immiscibility in supercooled melts. There is no consistent thermodynamic explanation for this interaction between components in different phases and under different conditions. Neither is there a correct thermodynamic description of the system; and all known descriptions [12][13][14][15] were inaccurate, which impeded the interpretation of observed facts. Therefore, thermodynamic description and evaluation of the system and analysis of equilibrium and metalstable phase transformations in this system are important and pending tasks. THERMODYNAMIC PROPERTIES OF LIQUID ALLOYSMixing Enthalpies. The mixing enthalpy of melts for the system was investigated for the first time in [16] at 1473 K in the copper-enriched region. A high-temperature calorimeter was used for this purpose: solid cobalt specimens heated to the experimental temperature were introduced into a crucible with liquid copper. Therefore, seven partial enthalpies of cobalt dissolution were established over the ra...

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“…This approximation is justified by a systematic cancellation of intra-and interatomic Coulomb effects 1111. Once the microscopic knowledge of the sp impurity states has been achieved, the next step is to use it in order to calculate the thermodynamical properties of the corresponding dilute alloys as it was already done successfully for transition impurities in transition or noble metals; initial slope and curvature of heats of formation and excess entropies [9,13,141. By using an analogous sp impurity model, satisfying results have already been obtained on the solubility of light interstitial atoms in transition metals 115, 16, 171.…”

Section: Introductionmentioning

confidence: 99%

Simple Electronic Structure Calculation of Substitutional sp Impurities in α‐Iron

Demangeat

Parlebas

1980

Physica Status Solidi (b)

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on the occasion of his 75th birthday Taking into account a Slater-Koster f i t to first-principles band structures for the host, a simple tight-binding model is proposed for the electronic structure of sp impurities (Al, Si, P ... Sb) substituted in ferromagnetic metals. The aim of the model is t o extend calculations t o future more complicated problems like chemical binding energies between point defects. The method is applied to dilute cc-iron based alloys: it is shown that a localized impurity model gives reasonable accord with experimental data on saturation magnetization, every time the dilution law is almost satisfied (@A], E S i , E P ) .E n utilisant un ajustement de type Slater-Koster B partir du spectre de dispersion du mktal pur obtenu d'apr& les "premiers principes", nous proposons un modble simple de liaisons fortes pour calculer la structure 6lectronique des impuretea sp (A], Si, P ... Sb) en substitution dans un mittal ferromagn6tique. Le but du modble est de pouvoir se genkraliser pour traiter des problbmes plus compliqu6s comme l'ktude (en cours) des knergies chimiques d'interaction entre dkfauts ponctuels. NOUS appliquons notre mtithode au cas des alliages dilues B base de fer a: nous montrons qu'un modele de potentiel d'impuretk localisk fournit des rksultats en accord avec les donn6es expkrimentales sur les moments B saturation, ceci, B chaque fois que la loi de dilution est B peu pr&s satisfaite (&Al, G S i , GP).

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Enthalpy of formation and excess entropy for dilute copper-based alloys: Experimental and theoretical study

Cited by 25 publications

References 18 publications

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. III. Copper-chromium system

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. III. Copper-chromium system

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. V. Copper-cobalt system

Simple Electronic Structure Calculation of Substitutional sp Impurities in α‐Iron

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