Influence of Copper Additives on Heat Capacity and Thermodynamic Functions of A7E Brand Aluminum
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LLURGY OF NONFERROUS METALS
Influence of Copper Additives on Heat Capacity and Thermodynamic Functions of A7E Brand Aluminum I. N. Ganievd, *, A. R. Rashidovb, **, H. O. Odinazodaa, ***, A. G. Safarovc, ****, and J. H. Jayloevd, ***** a
Osimi Tajik Technical University, Dushanbe, 734042 Republic of Tajikistan Institute of Energy of Tajikistan, Bohtariyon, Khatlon oblast, 735162 Republic of Tajikistan c Umarov Physical-Technical Institute, Academy of Sciences of the Republic of Tajikistan, Dushanbe, 734063 Republic of Tajikistan dNikitin Institute of Chemistry, Academy of Sciences of the Republic of Tajikistan, Dushanbe, 734063 Republic of Tajikistan *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] ****[email protected] *****[email protected] b
Received August 19, 2019; revised March 13, 2020; accepted March 18, 2020
Abstract—The economic feasibility of applying aluminum as a conductor is explained by the favorable ratio of its cost (which has remained almost constant for many years) to the cost of copper. When using conducting aluminum alloys to fabricate thin wire, winding wire, etc., some difficulties can appear in connection with their insufficient strength and small number of kinks before fracture. In recent years, aluminum alloys have been developed which possess strength characteristics, making it possible to apply them as conductors even in the soft state. One promising consumer of aluminum is the electrotechnical industry. From here, the development of new compositions of alloys based on this metal is very urgent. The temperature dependence of the heat capacity of A7E aluminum alloys with copper is determined experimentally and the variations in their thermodynamic functions are calculated. Investigations are carried out using computers and the Sigma Plot program. Polynomials of the temperature dependence of the heat capacity and variations in thermodynamic functions (enthalpy, entropy, and Gibbs energy) of these alloys and a reference alloy (Al of the A5N brand), which have the correlation coefficient Rcorr = 0.992–0.998, are established. It is shown that heat capacity of A7E brand aluminum decreases with an increase in the copper content and increases with an increase in temperature. The enthalpy and entropy of alloys of A7 brand aluminum with copper increase with an increase in the copper fraction and decrease with an increase in temperature. The inverse dependence is characteristic of the Gibbs energy. Keywords: A7Е brand aluminum, copper, reference sample (A5N brand Al), heat capacity, cooling mode, enthalpy, entropy, Gibbs energy DOI: 10.3103/S1067821220040045
INTRODUCTION Various physicochemical properties of aluminum alloys with copper are reported in publications. In particular, the authors of [1] investigated heat capacity of aluminum of the os.-ch. brand (special purity grade— 99.9995% Al) and A7E brand in the cooling mode. A comparison of these data with the data of [2–4] showed satisfactory coincidence. For example, С р0 = 1140 J/(kg K) was found
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