Features of the hereditary influence of the structure of Al–La, Al‑Sc, AND Al‑Sr ligatures on the structure and properties of the Al‑Si–Mg alloy

The results of comparative studies of the modifying ability of La, Sc (REM group) and Sr (AEM group) in the processing of the АК9ch alloy (Al-Si-Mg system) are presented. The elements were introduced into the melt with AlLa12, AlSc2, and AlSr10 masteralloys in the same amount – 0.25 wt.%. The effect of the elements on the microstructure, mechanical properties and electrical conductivity in the cast state at room temperature was evaluated. According to the values of electrical conductivity, the uniformity of the structure in the height of the experimental casting “Plate” was indirectly estimated. Modification to varying degrees contributed to an increase in the mechanical properties and the electrical conductivity of the АК9ch alloy. The maximum increase in the ultimate strength by 60–66 % was observed, when modifying with Sr additives, but it increases the hardness of HB and the relative elongation of the alloy to a lesser extent compared to modifying La and Sc. Modifiers from the REM group (La and Sc) changed the morphology of the main phases in different ways. When modified was of La, the morphology of eutectic silicon crystals changed from lamellar to fibrous, which corresponds to the results of studies by other authors. Modification with Sc additives caused similar changes in the morphology of eutectic silicon and partial grain-refine of α-Al dendrites. The greatest modifying and grain-refying effect on eutectic silicon crystals and α-Al dendrites was exerted by strontium, which belongs to alkaline-earth metals. The modification increases the electrical conductivity of the alloy, which reflects changes in the structure. The maximum increase in electrical conductivity caused modification alloy of the Sr. At the same time, the electrical conductivity of the casting practically does not change in height, which indirectly indicates an increase in the uniformity of the microstructure.

1. Stojanovic B., Bukvic М., Epler I.Application of aluminum and aluminum alloys in engineering. Applied Engineering Letters, 2018, vol. 3, no. 2, pp. 52–62.

2. Nappi C. The global aluminium industry 40 years from 1972. World Aluminium, 2013, 27 p.

3. Dudin M. N., Voykova N.A., Frolova E. E. [et al.] Modern trends and challenges of development of global aluminum industry. Metalurgija, 2017, vol. 56, pp. 255–258.

4. Djurdjević M. B., Odanović Z., Pavlović‑Krstić J. Melt quality control at aluminum casting plants. Metallurgical & Materials Engineering, 2010, vol. 16, pp. 63–76.

5. Nikitin V. I., Nikitin K. V. Nasledstvennost’ v lityh splavah [Heredity in cast alloys]. Moscow, Mashinostroenie‑1 Publ., 2005.

6. Nikitin K. V., Nikitin V. I., Timoshkin I. Yu. Upravlenie kachestvom lityh izdelij iz alyuminievyh splavov na osnove yavleniya strukturnoj nasledstvennosti [Quality management of cast products from aluminum alloys based on the phenomenon of structural heredity]. Moscow, Radunitsa Publ., 2015.

7. Selyanin I. F., Deev V. B., Kukharenko A. V. Resource‑saving and environment‑saving production technologies of secondary aluminum alloys. Russ. J. Non-Ferr. Met., 2015, vol. 56, iss. 3, pp. 272–276.

8. Deev V. B., Selyanin I. F., Ponomareva K. V. [et al.] Fast cooling of aluminum alloys in casting with a gasifying core. Steel in Translation, 2014, no. 44, pp. 253–254.

9. Nikitin V. I., Nikitin K. V. O klassifikacii modifikatorov dlya polucheniya litejnyh i deformiruemyh splavov [On the classification of modifiers for producing cast and wrought alloys]. Metallurgiya mashinostroeniya = Metallurgy of mechanical engineering, 2020, no. 6, pp. 8–17.

10. McCartney D. G. Grain refining of aluminium and its alloys using inoculants. International Materials Reviews, 1989, vol. 34, no. 5, pp. 247–260.

11. Murty B. S., Kori S.A., Chakraborty M. Grain refinement of aluminium and its alloys by heterogeneous nucleation and alloying. International Materials Reviews, 2002, vol. 47, no. 1, pp. 3–29.

12. Sigworth G. K. The modification of Al–Si casting alloys: Important practical and theoretical aspects. Inter. J. Metalcast, 2008, vol. 2, no. 2, pp. 19–40.

13. Rathod N. R., Manghani J. V. Effect of modifier and grain refiner on cast Al‑7Si aluminum alloy: a review. Inter. J. Emerging Trends in Engineering and Development, 2012, vol. 5, no. 2, pp. 574–581.

14. Faraji M., Katgerman L. Grain refinement and modification in hypoeutectic Al–Si alloys. Foundry Trade Journal, 2010, vol. 184, pp. 315–318.

15. Fang Q., Granger D. Porosity formation in modified and unmodified A356 alloy castings. AFS Trans., 1989, no. 97, pp. 989–1000.

16. Safwan M.A. Al‑Qawabah, Adnan I. O. Zaid. Different methods for grain refinement of materials. International journal of scientific & engineering research, 2016, vol. 7, iss. 7, pp. 1133–1140.

17. Rana R. S., Rajesh Purohit, Das S. Reviews on the influences of alloying elements on the microstructure and mechanical properties of aluminum. International journal of scientific and research publications, 2012, vol. 2, iss. 6, pp. 1–7.

18. Timpel M., Wanderka N., Schlesiger R. [et al.] The role of strontium in modifying aluminium‑silicon alloys. Acta Materialia, 2012, vol. 60, iss. 9, pp. 3920–3928.

19. Averkin A. I., Korchunov B. N., Nikanorov S. P., Osipov V. N. The effect of strontium on the mechanical properties of aluminum‑silicon alloy. Technical Physics Letters, 2016, vol. 42, no. 2, pp. 201–203.

20. Chandra Sekhar Rao P. V., Satya Devi A., Basava Kumar K. G. Influence of melt treatments on dry sliding wear behavior of hypereutectic Al‑15Si‑4Cu cast alloys. Jordan journal of mechanical and industrial engineering, 2012, vol. 6, no. 1, pp. 55–61.

21. Makhlouf M. On the mechanism of modification of the aluminum‑silicon eutectic by strontium: the role of nucleation. International journal of metalcasting, 2010, no. 4, pp. 47–50.

22. McDonald S. D., Dahle A. K., Taylor J.A., John St. Eutectic grains in unmodified and strontium‑modified hypoeutectic aluminum‑silicon alloys. Metallurgical and materials transactions A, 2004, vol. 35, no. 6, pp. 1829–1837.

23. McDonald S. D., Nogita K., Dahle A. K. Eutectic grain size and strontium concentration in hypoeutectic aluminium‑silicon alloys. Journal of alloys and compounds, 2006, vol. 422, iss. 1–2, pp. 184–191.

24. Nogita K., McDonald S. D., Dahle A. K. Eutectic Modification of Al‑Si Alloys with Rare Earth Metals. Materials Transactions, 2004, vol. 45, no. 2, pp. 323–326.

25. Xing P., Gao B., Zhuang Y. [et al.] On the modication of hypereutectic Al‑Si alloys using rare earth. Er. Acta Metall. Sin. (Engl. Lett.), 2010, vol. 23, no. 5, pp. 327–333.

26. Alkahtani S.A., Elgallad E. M., Tash M. M. [et al.] Effect of rare earth metals on the microstructure of Al‑Si based alloys. Materials, 2016, vol. 9, no. 45, pp. 1–13.

27. Ri E. Kh., Ri Kh., Goncharov A. V. Effect of Al–Y–Ce–La master alloy on structure formation, liquation processes and properties of AK7ch silumine (AL9). Proceedings of the ICMTMTE 2019. MATEC Web Conf., 2019, vol. 298, no. 56, pp. 1–6.

28. Gopi K. S. Effect of strontium modification and heat treatment on microstructure of Al‑319 alloy. International journal on theoretical and applied research in mechanical engineering, 2013, vol. 2, iss. 1, pp. 53–56.

29. Lamikhov L. K., Samsonov G. V. O modificirovanii alyuminiya i splava AL7 perekhodnymi metallami [On the modification of aluminum and AL7 alloy with transition metals]. Cvetnye metally = Non-ferrous metals, 1964, no. 1, p. 24.

30. Nikitin K. V., Nikitin V. I., Krivopalov D. S. [et al.] Vliyanie razlichnyh vidov obrabotki na strukturu, plotnost’ i elektroprovodnost’ deformiruemyh splavov sistemy Al–Mg [Influence of various types of processing on the structure, density and electrical conductivity of deformed alloys of the Al–Mg system]. Izvestiya vuzov. Cvetnaya metallurgiya = News of universities. Nonferrous metallurgy, 2017, no. 4, pp. 46–52.

31. Prukkanon W., Srisukhumbowornchai N., Limmaneevichitr Ch. Modification of hypoeutectic Al–Si alloys with scandium. Journal of alloys and compounds, 2009, vol. 477, pp. 454–460.

32. Kaiser M. S., Basher M. R., Kurny A. S. W. Effect of scandium on the cast Al–Si–Mg alloy. Proceedings of the international conference on mechanical engineering: ICME09-RT-55. Dhaka, 2009, pp. 1–6.