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ArticleName Change of eutectic morphology in Mg – Al – Ca – Mn system alloys in heat treatment process
DOI 10.17580/tsm.2015.10.07
ArticleAuthor Koltygin A. V., Nikitina A. A., Bazhenov V. E.

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

A. V. Koltygin, Assistant Professor, Casting Process Technology Chair, e-mail:
A. A. Nikitina, Post-Graduate Student, Casting Process Technology Chair
V. E. Bazhenov, Senior Lecturer, Junior Researcher, Casting Process Technology Chair


The process of crystallization of Mg – 6.3% Al – 3.7% Ca – 0.3% Mn and Mg – 4.5% Al – 2% Ca – 0.5% Mn alloys was considered with application of modeling of the state diagram Mg – Al – Ca – Mn in the Thermo-Calc program. Their phase content in equilibrium conditions was researched. There was made a definition that both alloys are crystallized in the area of formation of Al2Ca compound, and there should be no calcium compounds, having such composition of researched alloys in equilibrium structure. According to the state diagrams, the equilibrium structure of both alloys is a magnesium solid solution with inclusions of manganous Al4Mn phase and areas of eutectic isolations of intermetallic Al2Ca phases and a small amount of -phase (Mg17Al12), placed along the grain boundaries. There was researched the influence of heat treatment on morphology of eutectic isolations of Al2Ca phase in alloys. Cast alloy samples were annealed during 20, 30, 50 and 100 hours at the temperature of 490 °C for Mg – Al 6.3% – 3.7% Ca alloy and at the temperature of 500 °C for Mg – 4.5% Al – 2.0% Ca alloy with following air hardening at the room temperature. The morphology of isolations of Al2Ca phase was defined by deep etching of samples with dissolution of solid magnesium solution (Mg), when the Al2Ca phase was almost not etched. Research of samples by electron microscopy mehods defined that the as-cast microstructure of investigated alloys consists of primary crystals of magnesium solid solution and eutectic isolations of Al2Ca phase, having the shapes of plates or hyeroglyphs. During the annealing of researched alloys, the shape of eutectic inclusions is changed from plate to compact, which should make a positive effect on mechanical properties of the alloys.
This work was carried out within the State work “Scientific-research works (basic research, applied research and experimental development)” of the State task of the Ministry of Education and Science of Russian Federation in the sphere of scientific activities for 2014–2016. (task No. 2014/113).

keywords Cast alloy, magnesium alloy, heat treatment, eutectics, morphology, solid solution, annealing, casting

1. Luo. A. A. Magnesium: Current and potential automotive applications. Journal of Metals. 2002. Vol. 54, iss. 2. pp. 42–48.
2. Wenwen D., Yangshan S., Xuegang M., Feng X., Min Z., Dengyun W. Microstructure and mechanical properties of Mg – Al based alloy with calcium and rare earth additions. Materials Science and Engineering: A. 2003. Vol. 356, iss. 1–2. pp. 1–7.
3. Bamberger G. M., Dehm G. Trends in the Development of New Mg Alloys. Annual Review of Material Research. 2008. Vol. 38. pp. 505–533.
4. Suzuki A., Saddock N. D., Jones J. W., Pollock T. M. Solidification paths and eutectic intermetallic phases in Mg – Al – Ca ternary alloys. Acta Materialia. 2005. Vol. 53, iss. 9. pp. 2823–2834.
5. Aljarrah M., Medraj M. Thermodynamic modelling of the Mg – Ca, Mg – Sr, Ca – Sr and Mg – Ca – Sr systems using the modified quasichemical model. Calphad. 2008. Vol. 32, iss. 2. pp. 240–251.
6. Rokhlin L. L., Nikitina N. I., Volchenkova V. A. Issledovanie bogatykh magniem splavov Mg – Al2Ca (Investigation of magnesium-rich alloys Mg – Al2Ca). Metally = Metals. 2006. No. 2. pp. 104–108.
7. Tkachenko V. G., Kim K. H., Moon B. G., Vovchok A. S. Design and microstructural analysis of magnesium alloys for dynamical applications. Journal of Materials Science. 2011. Vol. 46, iss. 14. pp. 4880–4895.
8. Terada Y., Ishimatsu N., Mori Y., Sato T. Eutectic Phase Investigation in a Ca-added AM50 Magnesium Alloy Produced by Die Casting. Materials Transactions. 2005. Vol. 46, No. 2. pp. 145–147.
9. Koltygin A. V., Bazhenov V. E., Belova E. A., Nikitina A. A. Development of a magnesium alloy with good casting characteristics on the basis of Mg – Al – Ca – Mn system, having Mg – Al2Ca structure. Journal of Magnesium and Alloys. 2013. Vol. 1, iss. 3. pp. 224–229.
10. Lados D. A., Apelian D. Solution Treatment Effects on Microstructure and Mechanical Properties of Al–(1 to 13 Pct)Si–Mg. Cast Alloys. Metallurgical and Materials Transactions: B. 2011. Vol. 42B. pp. 171–180.
11. Tillova E., Chalupova M., Hurtalova L., Bonek M., Dobrzanski L. A. Structural analysis of heat treated automotive cast alloy. Journal of Achievements in Materials and Manufacturing Engineering. 2011. Vol. 47, iss. 1. pp. 19–25.
12. El-Labban H. F., Mahmoud E. R. I. Modification of microstructures for hypoeutectic, eutectic and hypereutectic Al – Cu binary alloys. International Journal of Cast Metals Research. 2015. Vol. 28, iss. 2. pp. 81–88.
13. Gupta A. K., Prasad B. K., Pajnoo R. K., Das S. Effects of T6 heat treatment on mechanical, abrasive and erosive-corrosive wear properties of eutectic Al – Si alloy. Transactions of Nonferrous Metals Society of China. 2012. Vol. 22, iss. 5. pp. 1041–1050.
14. Belov N. A., Savchenko S. V., Belov V. D. Atlas mikrostruktur promyshlennykh siluminov (Atlas of microstructures of industrial silumins). Moscow : MISiS, 2009. 204 p.
15. Somov A. I., Tikhonovskiy M. A. Evtekticheskie kompozitsii (Eutectic compositions). Mosocw : Metallurgiya, 1975. 304 p.

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