The effect of copper additives on the heat capacity and thermodynamic functions of A7E grade aluminum

The economic feasibility of using aluminum as a conductive material is explained by the favorable ratio of its cost to the cost of copper. In addition, one should take into account the factor that the cost of aluminum remains practically unchanged for many years. When using conductive aluminum alloys for the manufacture of thin wire, winding wire, etc. certain difficulties may arise in connection with their insufficient strength and a small number of kinks before fracture. In recent years, aluminum alloys have been developed with strength characteristics that allow them to be used as a conductive material even in a soft state. One of the promising applications of aluminum is the electrical industry. Hence, the development of new alloy compositions based on this metal is very relevant. The temperature dependence of the heat capacity of A7Е grade aluminum alloys with copper was experimentally determined, and changes in their thermodynamic functions were calculated. The studies were carried out in cooling mode using computer hardware and Sigma Plot software. Polynomials were established for the temperature dependence of the heat capacity and changes in thermodynamic functions (enthalpy, entropy, and Gibbs energy) of these alloys and a reference standard (A5N grade Al) characterized by a correlation coefficient Rcorr = 0.992+0.998. It was shown that the heat capacity of A7E grade aluminum decreases with increasing copper content, and increases with rising temperature. The enthalpy and entropy of A7 grade aluminum alloys with copper decrease with increasing copper content, and increase with rising temperature. The value of Gibbs energy is characterized by an inverse relationship.

1. Nizomov Z., Gulov B., Ganiev I.N., Saidov R.Kh, Obi-dov F U., Eshov B.B. Study of the temperature dependence of the specific heat of aluminum grades OSCh and A7. Doklady ANRespubliki Tadzhikistan. 2011. Vol. 54. No. 1. P. 53—59 (In Russ.).

2. Zolotorevskii V.S., Belov N.A. Metallurgy of foundry aluminum alloys. Moscow: MISIS, 2005 (In Russ.).

3. Beletskii V.M., Krivov G.A. Aluminum alloys (structure, properties, technology, application). Ed. I.N. Fridlyander. Kiev: KOMITEKh, 2005 (In Russ.).

4. Madzhidov Kh, Aminov B, Safarov M, Vakhobov A., Obi-dovF.U Heat capacity of highly pure aluminum depending on temperature. Doklady AN Respubliki Tadzhikistan. 1990. Vol. 33. No. 6. P. 380—383 (In Russ.).

5. Usov V.V., ZaimovskiiA.S. Conductor, rheostat and contact materials. Materials and alloys in electrical engineering. Vol. II. Moscow.: Gosenergoizdat, 1957 (In Russ.).

6. Somasekharan A.C., Murr L.E. Microstructures in friction-stir welded dissimilar magnesium alloys and magnesium alloys to 6061-T6 aluminum alloy. Mater. Cha-ract. 2004. Vol. 52. No. 1. P. 49—64.

7. Menan F., Henaff G. Synergistic action of fatigue and corrosion during crack growth in the 2024 aluminum alloy. Procardia Eng. 2010. Vol. 2. No. 1. P. 1441—1450.

8. Hu X.W, Jiang F.G., Yan H. Effects of rare earth Er additions on microstructure development and mechanical properties of die-cast ADC12 aluminum alloy. J. Alloys Compd. 2012. P. 538—544.

9. Fragomeni J., Wheeler R., Jata K.V Effect of single and duplex aging on precipitation response, microstructure, and fatigue crack behavior in Al—Li— Cu alloy AF/C- 458. J. Mater. Eng. Perform. 2005. Vol. 14. No. 1. P. 18—27.

10. Mondolfo L.F. Structure and properties of aluminum alloys. Moscow: Metallurgiya, 1979 (In Russ.).

11. Yan X.Y, Chang Y.A., Xie FY, Chen S.L., Zhang F, Daniel S. Calculated phase diagrams of aluminum alloys from binary Al—Cu to multicomponent commercial alloys. J. Alloys Compd. 2001. Vol. 320. No. 2. P 151— 160.

12. Liu L., Ren D., Liu F. A review of dissimilar welding techniques for magnesium alloys to aluminum alloys. Materials. 2014. Vol. 7. No. 5. P. 3735—3757.

13. Wang M.J., Chen L., Wang Z.X. Effect of rare earth addition on continuous heating transformation of a high speed steel for rolls. J. Rare Earths. 2012. Vol. 30. P. 84—89.

14. Chen X.G. Growth mechanisms of intermetallic phases in DC cast AA1XXX alloys. Essential Readings in Light Metals. Vol. 3. Cast shop for aluminum production. 2013. P. 460—465.

15. Ivantsov G.P. Heating of metal (theory and methods of calculation). Sverdlovsk; Moscow: Metallurgizdat, 1948 (In Russ.).

16. Bagnitskii V.E. Feedback in the physical phenomena. Germany: LAP (Lambert Acad. Publ.), 2014 (In Russ.).

17. Kirov S.A., Saletskii A.M., Kharabadze D.E. The study of transport phenomena in the air. Description of problem No. 219 of the general physical workshop «Molecular physics». Moscow: OOP Fiz. facul’teta MGU, 2013 (In Russ.).

18. Ganiev I.N., Safarov A.G., Odinaev F.R., Yakubov U.Sh., Kabutov K. Temperature dependence of the specific heat and the changes in the thermodynamic functions of a bismuth-bearing AZh4.5 alloy. Russ. Metallurgy (Metally). 2020. Vol. No. 1. P. 17-24.

19. Ganiev I.N., Nazarova M.T, Yakubov U.Sh., Safarov A.G., Kurbonova M.Z. Influence of lithium on specific heat capacity and changes in the thermodynamic functions of aluminum alloy AB1. High Temp. 2020. Vol. 58. No. 1. P. 58-63.

20. Ganiev I.N., Safarov A.G., Odinaev F.R., Yakubov U.Sh., Kabutov K. Temperature dependence of heat capacity and the variation in thermodynamic function of the AZh 4.5 alloy doped with tin. Russ. J. Non-Ferr. Met. 2019. Vol. 60. No. 2. P. 139-145.

21. Obidov Z. Thermophysical properties and thermodynamic functions of the beryllium, magnesium, and praseodymium alloyed Zn-55Al alloy. High Temp. 2017. Vol. 55. No. 1. P. 150-153.

22. Ganiev I.N., Muminov Kh. Kh., Ganieva N.I. et al. Installation for determination of heat capacity and thermal conductivity of solid bodies: Pat. TJ877 (Tadzhikistan). 2017.