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MATERIALS SCIENCE
Название Ultimate grain refinement in aluminium alloys of the Al – Zn – Mg – Cu system with zirconium
DOI 10.17580/tsm.2018.10.08
Автор Bochvar S. G.
Информация об авторе

Baykov Metallurgy and Materials Institute of the Russian Academy of Sciences, Moscow, Russia:

S. G. Bochvar, Senior Researcher, e-mail: sgbochvar@yandex.ru

Реферат

It is a well-known fact that the quality of ingots and the resultant properties of semi-finished and final products are, to a large extent, governed by how fine the structure of the ingots is. It is for this reason that a lot of attention is given to identifying the inoculant and the inoculation process that would work best as microaddition to aluminium alloys cast in ingots. Various compositions of the Al – Ti – B alloy have recently been used widely as inoculants. However, when casting zirconium containing alloys, a “poisoning” effect occurs, i. e. when titanium diborides become inert as nucleation centres and drop out of the doping process. That is why in the case of high strength alloys of the Al – Zn – Mg – Cu – Zr system it is important to find a similar addition alloy that could replace the Al – Ti – B alloy while producing a strong doping effect. The author managed to obtain a non-dendritic structure with no Zr compounds exceeding 1 micron separated during crystallization of the Al – Zn – Mg – Cu – Zr alloy. Liquid metal in ingots of 40 mm in diameter were exposed to ultrasound and a rod was used with the microaddition of 0.02% Zr (Zr concentration in the burden was 0.12%). The microaddition of 0.01%Zr (Zr concentration in the burden was 0.14%) was used when two ultrasonic sources were in action. The paper shows a difference in the eutectic morphology in the structures of high strength alloys of the Al – Zn – Mg – Cu – Zr system in the case of dendritic versus non-dendritic crystallization, which can be explained by differing eutectic crystallization sequences of the casting techniques compared. Thus, during crystallization of non-dendritic grains the eutectic precipitation occurs immediately and the precipitates, which have a continuous plate-like shape, form between the grains, whereas during crystallization of dendritic grains the eutectic precipitates form between the dendrite branches and have a spherical shape. There is a constant amount of eutectic in both cases. So a greater border area would equate to a finer eutectic, which is characteristic of non-dendritic crystallization. This suggests a possibility of using a shorter homogenization time in the case of nondendritic crystallization.

This research was carried out under the Governmental Assignment No. 007-00129-18-00.

Ключевые слова Aluminium alloys, non-dendritic grain, casting, inoculation, grain refinement, zirconium, ultrasound, cavitation
Библиографический список

1. Bondarev B. I., Napalkov V. I., Tararyshkin V. I. Inoculation of aluminium wrought alloys. Moscow : Metallurgiya, 1979. 224 p.
2. Makarov G. S. Extrusion ingots made of aluminium alloys with magnesium and silicon. Moscow : Intermet Inzhiniring, 2011. 528 p.
3. Liu X., Liu Y., Yan D., Han Q., Wang X. Aluminum alloys with tailored TiB2 particles for composite applications. TMS 2017 Annual Meeting and Exhibition, SanDiego, CA. 2017. pp. 181–186.
4. Bochvar S. G., Eskin G. I. Acoustic cavitation as an efficient technique for ultimate grain refinement of aluminium alloys subjected to ladle inoculation. Tekhnologiya legkikh splavov. 2012. No. 1. pp. 9–17.
5. Puga H., Prokic M., Van Dongen N. Breakthrough in ultrasonic assisted industrial continuous casting. Aluminium International Today. Sept. – oct. 2014. pp. 1–3.
6. Schloz J. D. Fundamentals of Grain Refining Aluminum Alloys. Light Metal Age. 2010. No. 8. pp. 30–37.
7. Wang Y., Zhou L., Fan Z. Mechanism of zirconium poisioning effect on TiB2 inoculation in aluminium alloys. Light Metals. 2016. pp. 725–729.
8. Wang X., Liu Z., Dai W., Han Q. On the Understanding of Aluminum Grain Renement by Al – Ti – B Type Master Alloys. Metallurgical and Materials Transaction B. 2015. Vol. 46B. pp. 1620–1625.
9. Belotserkovets V. V. Regularities of producing a non-dendritic structure in aluminium alloys with zirconium. Tekhnologiya legkikh splavov. 2013. No. 4. pp. 160–168.
10. Bochvar S. G. On the new approach to ultimate structural refinement of aluminium ingots in continuous casting by way of ladle inoculation and acoustic treatment of melted aluminium. Tekhnologiya legkikh splavov. 2011. No. 1. pp. 12–21.
11. OST 1 90026–80. High purity aluminium wrought alloys. Grades. Introduced: 01.11.1980.
12. Bochvar S. G., Teleshov V. V., Eskin G. I. Ways to enhance the quality of V65 cast billets for rivet wires. Tekhnologiya legkikh splavov. 2012. No. 1. pp. 57–63.
13. Zolotorevsky V. S., Teleshov V. V. Identifying optimum time of heating for hardening by analyzing the structure of aluminium alloy ingots. Metal Science and Heat Treatment. 1970. No. 7. pp. 44–49.

Language of full-text русский
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