Arconik SMZ, Samara, Russia:

V. V. Yashin, Manager, e-mail: Vasiliy.Yashin@arconic.com

I. A. Latushkin, Lead Specialist, e-mail: ilya.latushkin@arconic.com

Freiberg University of Mining and Technology, Freiberg, Germany:

A. S. Kabanov, Research Fellow at the Institute of Metal Forming

Samara National Research University, Samara, Russia:
E. V. Aryshensky, Associate Professor at the Department of Materials Technology and Aviation Materials

The work conducted as part of this research focused on understanding how microalloying of the AlMg5 alloy with the transition metals of Zr, Sc and Nb can impact the grain structure of a cast billet. A complete factorial experiment was carried out during which different concentrations of the above elements were applied – from 0.1 to 0.3 %. The experiment provided a quantitative analysis of the inoculation effect produced by each of the studied transition metals. An induction furnace was used to produce ingots, which were chill cast. Metallographic specimens were prepared for each casting and analysed for microstructure with a 100:1 magnification optical microscope. The results of the microstructural analysis indicate a strong inoculation effect produced by zirconium and scandium and a low effect when niobium is used for grain refinement. The authors were able to obtain ingots with a grain structure with the maximum grain size being 23 μm versus the initial dendritic structure of a cast ingot (with the interdendritic distance of 153 μm) produced under the same conditions but not inoculated with transition metals. A curve was built showing how the grain size is governed by the total amount of rare earth elements, i. e. Zr, Sc and Nb. With the help of regression analysis the authors came up with an analytical expression for the above relationship.
This research was funded by the Russian Science Foundation, Project 18-79-10099.

1. Drits M. E., Toropova L. S., Bykov Yu. G., Elagin V. I., Filatov Yu. A. The structure and properties of the Al – Sc and Al – Mg – Sc alloys. Metallurgy and science of non-ferrous alloys. Moscow : Nauka, 1982. pp. 213–223.
2. Luts A. R., Suslina A. A. Aluminium and its alloys : tutorial. Samara : Samarsky gosudarstvenny tekhnichesky universitet, 2013. 81 p.
3. Mondolfo L. F. Aluminium alloys: Structure and properties (Translated from English). Moscow : Metallurgiya, 1979. 640 p.
4. Recrystallisation of metallic materials. Ed. by F. Hessner. Translated from English by Ch. V. Kopetsky. Moscow : Metallurgiya, 1982. 351 p.
5. Zakharov V. V. The effect of scandium on the structure and properties of aluminium alloys. Metallovedenie i termicheskaya obrabotka metallov. 2003. No. 7. pp. 7–15.
6. Drits M. E., Toropova L. S., Bykov Yu. G. The effect of REMs on the mechanical properties of the Al – 6.5% Mg alloy. MiTOM. 1980. No. 10. p. 35.
7. Davydov V. G. et al. On inoculating of aluminium alloys with scandium and zirconium additions. MiTOM. 1996. No. 8. pp. 25–30.
8. Filatov Yu. A. Inoculation of the Al – Mg alloys with scandium: Search for deeper understanding. Tekhnologiya legkikh splavov. 2015. No. 2. pp. 19–22.
9. Li H. et al. Grain refinement mechanism of as-cast aluminum by hafnium. Transactions of Nonferrous Metals Society of China. 2016. Vol. 26, Iss. 12. pp. 3059–3069.
10. Johansen A. Microstructures and properties of aluminium-magnesium alloys with additions of manganese, zirconium and scandium. Trondheim : Norwegian University of Science and Technology, 2000. 230 p.
11. Zakharov V. V. Stability of the solid solution of scandium in aluminium. MiTOM. 1997. No. 2. p. 15–20.
12. Ganiev I. N., Narziev B. Sh., Safarov A. M. Effect of small additions of zirconium and similar elements on the electrochemical behaviour of aluminium. Proceedings of the Academy of Sciences of the Republic of Tadjikistan. 2007. Vol. 50, No. 3. pp. 255–260.
13. Yashin V. V., Aryshenskiy V. Yu., Latushkin I. A., Tepterev M. S. Substantiation of a manufacturing technology of flat rolled products from Al – Mg – Sc based alloys for the aerospace industry. Tsvetnye Metally. 2018. No. 7. pp. 75–82.
14. Yashin V. V. et al. Effect of microalloying the aluminium-magnesium system with transition and rare earth metals on the mechanical properties during thermomechanical processing. Proizvodstvo prokata. 2017. No. 8. pp. 42–48.
15. Aryshensky E. V. et al. How microalloying of the aluminium-magnesium system with rare earth and transition metals changes the structure evolution during thermomechanical processing. Proizvodstvo prokata. 2017. No. 4. pp. 4–11.
16. Wang F. et al. Revisiting the role of peritectics in grain refinement of Al alloys. Acta Materialia. 2013. Vol. 61, No. 1. pp. 360–370.
17. Feng W. et al. Crystallographic study of Al₃Zr and Al₃Nb as grain refiners for Al alloys. Transactions of Nonferrous Metals Society of China. 2014. Vol. 24, Iss. 7. pp. 2034–2040.
18. GOST 21073.2–75 Non-ferrous metals. Determination of grain size by grain calculation method (incl. Revision 1). Introduced: 01.07.1976.
19. Levinsky Yu. V. Phase diagrams of binary metallic systems. Vol. 1. Reference book. Moscow : Metallurgiya, 1990. 398 p.
20. Cherkasov V. V. et al. Al – Mg cast alloys inoculated with scandium: Formation of structure and properties. MiTOM. 1996. No. 6. pp. 30–32.
21. Kazakova E. F., Dmitrieva N. E., Dunaev S. F. Interaction of aluminium with niobium and scandium in equilibrium and non-equilibrium states. Vestnik Moskovskogo universiteta. 2015. Vol. 56, No. 1. pp. 41–47.
22. Milman Yu. V. et al. Structure and strength of the deformable Al – 5Mg alloys inoculated with scandium, zirconium and niobium. Elektronnaya mikroskopiya i prochnost materialov. 2015. No. 21. pp. 23–29.
23. Mansurov Yu. N., Rakhmonov J. U., Letyagin N. V., Finogeyev A. S. Influence of impurity elements on the casting properties of Al – Mg based alloys. Non-ferrous Мetals. 2018. No. 1. pp. 24–29.