National University of Science and Technology MISiS, Moscow, Russia:

N. A. Belov, Professor of the Department of Metal Forming
S. S. Mishurov, Leading Engineer
N. O. Korotkova, Post-Graduate Student of the Department of Metal Forming

¹National University of Science and Technology MISiS, Moscow, Russia ; ²Baikov Institute of Metallurgy and Materials Science, Moscow, Russia

T. K. Akopyan, Research Fellow^1,2, e-mail: aktorgom@gmail.com

Using both thermodynamic calculations and experimental analises, the Al – Ca – Fe – Si phase diagram near the aluminum corner has been studied. It is shown that the Al₄Ca intermetallic phase can be in equilibrium with the Al3Fe and Al₂CaSi₂ phases, which are included in the invariant eutectic reaction L → (Al) + Al₄Ca + Al₂CaSi₂ + Al₃Fe at 611 ^оC, 91.90% Al, 6.92% Ca, 0.68% Fe, and 0.50% Si. In accordance with the literary data and results of the experiments, the binary Al₃Fe iron-containing phase can be replaced by a ternary Al₁₀CaFe₂ phase. The solidification of all Al – Ca alloys should be completed via this invariant reaction. A study of the hypoeutectic alloys with calcium content up to 6 % (wt.), iron to 1% (wt.) and silicon to 1% (wt.), revealed a fine microstructure consisting of primary crystals of (Al) and eutectic colonies. Fe- and Si-bearing phases have favourable morphology. Coarse needle-like particles were not found. In accordance with the results of DSC analysis and calculation data, the solidification range of the considered alloys is very narrow and less than 50 degrees, which suggests excellent casting properties. In particular, according to the casting “pencil” and “harp” probes for the Al6Ca1Fe0.5Si alloy with minimal solidification range, it is not inferior to standard Al – Si alloys. Due to the results above, it can be conclude that the Al – Ca system is promising for the development of new casting aluminium alloys.

This work was financially supported by the Ministry of Education and Science of the Russian Federation within the implementation of the Agreement on subsidies No. 14.578.21.0220 (unique identifier of the project RFMEFI57816X0220).

1. Belov N. A., Naumova E. A., Akopyan T. K. Eutectic alloys based on aluminum: new alloying systems. Moscow : “Ore and Metals” Publishing House, 2016. 256 p.
2. Mondolfo L. F. Aluminium alloys: structure and properties. Butterworths, London, 1976.
3. Kevorkov D., Schmid-Fetzer R. The Al – Ca system, part 1: experimental investigation of phase equilibria and crystal structures. Z. Metallkd. 2001. No. 92. pp. 946–952.
4. Ozturk K., Chen L. Q., Liu Z.-K. Thermodynamic assessment of the Al – Ca binary system using random solution and associate models. Journal of Alloys and Compounds. 2002. No. 340. pp. 199–206.
5. Belov N. A., Naumova E. A., Alabin A. N., Matveeva I. A. Effect of scandium on structure and hardening of Al – Ca eutectic alloys. Journal of Alloys and Compounds. 2015. No. 646. pp. 741–747.
6. Kaufman J. G., Rooy E. L. Aluminum alloy castings: properties, processes, and applications. ASM International. Ohio, 2004.
7. Hatch J. E. Aluminum: properties and physical metallurgy. ASM International. Ohio, 1984.
8. Ji S., Yang W., Gao F., Watson D., Fan Z. Effect of iron on the microstructure and mechanical property of Al – Mg – Si – Mn and Al – Mg – Si die cast alloys. Materials Science & Engineering. 2013. Vol. 564. pp. 130–139.
9. Moustafa M. A. Effect of iron content on the formation of β-Al₅FeSi and porosity in Al – Si eutectic alloys. Journal of materials processing technology. 2009. No. 209. pp. 605–610.
10. Basak C. B., Hari Babu N. Morphological changes and segregation of β-Al₉Fe₂Si₂ phase: a perspective from better recyclability of cast Al – Si alloys. Materials & Design. 2016. No. 108. pp. 277–288.
11. Zolotorevskiy V. S., Belov N. A., Glazoff M. V. Casting aluminum alloys. Elsevier, Amsderdam, 2007.
12. Petzow G., Effenberg G. Ternary alloys: a comprehensive compendium of evaluated constitutional data and phase diagrams. Wiley-VCH; Weinheim, 1990. 647 p.
13. Belov N. A., Naumova E. A., Akopyan T. K. Effect of 0.3 wt%Sc on structure, phase composition and hardening of Al – Ca – Si eutectic alloys. Transactions of Nonferrous Metals Society of China. 2017. No. 4. pp. 741–746.
14. Belov N. A., Naumova E. A., Ilyukhin V. D., Doroshenko V. V. Structure and mechanical properties of Al – 6%Ca – 1%Fe alloy foundry goods, obtained by die casting. Tsvetnye Metally. 2017. Iss. 3. pp. 69–75.
15. Reference data for thermodynamic calculations. Available at: http://www.thermocalc.com. 2017 (accessed: 31.08.17).
16. Ratke L., Alkemper J. Ordering of the fibrous eutectic microstructure of Al-Al3Ni due to accelerated solidification conditions. Acta Materialia. 2000. Vol. 48. pp. 1939–1948.
17. Li X., Fautrelle Y., Ren Zh., Zhang Yu. , Esling C. Effect of a high magnetic field on the Al – Al₃Ni fiber eutectic during directional solidification. Acta Materialia. 2010. Vol. 58. pp. 2430–2441.
18. Plotkowski A., Rios O., Sridharan N., Sims Z., Unocic K., Ott R. T., Dehoff R. R., Babu S. S. Evaluation of an Al – Ce alloy for laser additive manufacturing. Acta Materialia. 2017. Vol. 126. pp. 507–519.
19. Böyük A., Engin S., Maral N. Microstructural characterization of unidirectional solidified eutectic Al – Si – Ni alloy. Materials Characterization. 2011. Vol. 62. pp. 844–851.
20. Fatemi-Jahromi F., Emamy M. An investigation into high temperature tensile behavior of hot-extruded Al – 15wt%Mg2Si composite with Cu – P addition. Manufacturing Science and Technology. 2015. Vol. 3. pp. 160–169.
21. Emamy M., Emami A. R., Tavighi K. The effect of Cu addition and solution heat treatment on the microstructure, hardness and tensile properties of Al–15%Mg2Si–0.15%Li composite. Materials Science and Engineering: A. 2013. Vol. 576. pp. 36–44.
22. Zhang J., Fan Z., Wang Y. Q., Zhou B. L. Microstructural development of Al–15 wt.% Mg2Si in-situ composite with michmetal addition. Materials Science and Engineering: A. 2000. Vol. 281. pp. 104–112.