Determination of Thermodynamic Quantities of Binary Metal Systems with Low Solubility of Components in the Solid α-Phase
Abstract
The method for determining the thermodynamic quantities: the partial enthalpy of dissolution , the activity coefficients and activities of the second component B in binary metallic systems with low solubility in the solid α-phase has been proposed. The algorithm for determining the above values is a sequence of preliminary calculations of the limiting and equilibrium distribution coefficients and construction of saturated solid solution lines for such systems with low solubility of the second component. Preliminarily obtained data are necessary for determining the partial enthalpy of dissolution and other quantities in the systems under study. Such a sequence of calculations is the proposed method for determining the thermodynamic parameters of dissolution. The values and temperature dependences of the dissolution enthalpy of component having a low solubility for such systems as Cd-Na, Cd-Tl, Te-Ga, Te-As, Te-Cu, Zn-Sn, as well as the activity coefficients and the activities of the second component in the saturating α-phase in these systems were determined. An analysis of obtained results on the enthalpy of dissolution shows that a change in the partial enthalpy with a change in the dissolution temperature is observed. When the temperature decreases from the melting point of the pure main component to the eutectic temperature, an increase in the partial enthalpies of dissolution of the second component is observed for studied systems. The Te-Ga system is characterized by a negative value . A negative value indicates an exothermic process of gallium dissolution in tellurium, in contrast to other systems in which the dissolution of the second component occurs with heat absorption. Analyzing the enthalpy of dissolution in the systems under study, it should be noted that the low values of < 2000 J/mol are characterized by the systems Cd-Na and Te-Ga. For systems Te-Cu, Te-As, Te-Tl, Zn-Sn > 15000 J/mol. Systems with a value > 15000 J/mol reveal a tendency to the occurrence of retrograde solubility in them. The difference in values is found to be more than two orders of magnitude for different systems.
Downloads
References
Lyakishev N.P. Phase diagrams of binary metal system. - Vol.1. - М.: Mashinostroyeniye, 1996. – 992 p.; Vol.2. - М.: Mashi-nostroyenoye, 1997. – 1024 p. (in Russian)
Kovtun G.P., Scherban’ A.P., Datsenko O.A. Determination of the limiting impurity distribution coefficients k0 limB in cadmium and zinc // Voprosy atomnoy nauki i tekhniki. Ser.: Vacuum, pure materials, superconductors. – 2002. – No. 1(12). – P. 151 155. (in Russian)
Kovtun G.P., Scherban’ A.P., Datsenko O.A. Calculation method for determining the limiting impurity distribution coefficients k0limB at the directional crystallization of metals // Voprosy atomnoy nauki i tekhniki. Ser.: Vacuum, pure materials, superconduc-tors. – 2003. – No. 5(13). – P. 3-6. (in Russian)
Scherban’ A.P. The limiting distribution coefficients of low-soluble impurities in metals // Journal of V.N. Karazin Kharkiv Na-tional University. Series Nuclei, particles, fields. – 2011. – No. 946. – Iss.1(49) – P. 75-80. (in Russian)
Kovtun G.P., Scherban’ A.P. Estimation of the solubility limit of low-soluble components under eutectic transformations in the binary metal systems // Problem of Atomic Science and Engineering. – 2014. – No. 1(89). – P. 37-40.
Scherban’ A.P., Datsenko O.A. Analysis of phase diagrams of binary metal systems in the field at low concentration of compo-nents // Journal of V.N. Karazin Kharkiv National University. Series Nuclei, particles, fields. – 2013. – No. 1069. – Iss. 4(60). – P. 95–99. (in Russian)
Shcherban A.P., Datsenko O.A., Kovtun G.P. Construction of Solidus Lines of Binary Metal Systems Having a Low Solubility of Components in the Solid Phase // Open Journal of Metal. – 2014. – Vol. 4. – P. 65-71.
Svellin R.A. Solid phase thermodynamics. – Metallurgiya, 1968. – 316 p.
Barthel J., Buhrig E., Hein К., Kuchař L. Cristallisation aus Schmelzen // Reference manual: Translation from German. - М.: Me-tallurgy, 1987. – 320 p. (in Russian).
Kröger F.A. Chemistry of imperfect crystals. – Translation under the editorship of Poltorak O.M., 1969. - 654 p.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
