Effect of Iron Content on Crystallization and Microstructure of EN AC-42000 Alloy
DOI:
https://doi.org/10.24425/afe.2025.153792Abstract
The paper presents research on evaluating the crystallization of Al-Si alloys with increased iron content and analysis of the associated phase transformations. This problem is significant with the growing importance of recycling aluminum alloys, which is justified economically and ecologically. The study concerns the cooling curves of EN AC-42000 alloy (EN AC-AlSi7Mg), into which iron (in the form of Al-Fe mortar - as a substitute for circulating scrap) was introduced with a content of 0.5 to 1.5wt.%. Analysis of crystallization by ATD and microstructure studies of eleven Al-Si-Mg alloys with varying iron content showed up to about 0.4 wt.% Fe, the iron phases formed do not significantly affect the microstructure. They enter into multiphase eutectics of the type α(Al)+(Mg2Si,Fe)+β(Si) or α(Al)+(AlXFeYSiZ)+β(Si), which crystallize after the formation of the double eutectic α(Al)+β(Si). In the range of about 0.5 to 0.9 wt.% Fe, there is a preneutic crystallization of iron phases, mainly the lamellar-neutectic β-Al5FeSi. At more than 1.0 wt.% Fe, the morphology of this phase becomes even more unfavorable (due to primary crystallization) and is accompanied by numerous clusters of shrinkage porosity.References
[1] MacKenzie, S.D., Totten, G.E. (2005). Analytical characterization of aluminum, steel, and superalloys. (1st ed.). Boca Raton: Taylor and Francis Group.
[2] Xinjin, Cao, & Campbell, J. (2006). Morphology of β-Al5FeSi phase in Al-Si cast alloys. Materials Transaction. 47(5), 1303-1312. https://doi.org/10.2320/matertrans. 47.1303.
[3] Taylor, J.A. (2004). The effect of iron in Al-Si cast alloys. In 35th Australian Foundry Institute National Conference, 31 October - 3 November 2004 (pp. 148-157). Australia: Australian Foundry Institute.
[4] Ebhota, W.S. Tien-Chien, J. (2018). Intermetallics formation and their effect on mechanical properties of Al-Si-X alloys. In Mahmood Aliofkhazraei (Eds.), Intermetallic Compounds - Formation and Applications (pp. 21-38). London, United Kingdom: IntechOpen.
[5] Taylor, J.A. (2012). Iron-containing intermetallic phases in Al-Si based casting alloys. Procedia Materials Science. 1, 19-33. DOI: 10.1016/j.mspro.2012.06.004.
[6] Zavadska, D., Tillova, E., Svesova, I., Chalupova, M., Kucharikova, L. & Belan, J. (2019). The effect of iron content on microstructure and porosity of secondary AlSi7Mg0.3 alloy. Periodica Polytechnica Transportation Engineering. 47(4), 283-289. https://doi.org/10.3311/PPtr.12101.
[7] Orozco-Gonzales, P., Castro-Roman, M., Martinez, A.I., Herrero-Trejo, M., Lopez, A.A. & Quispe-Marcatoma, J. (2010). Precipitation of Ferich intermetallic phase in liquid Al-13.58Si-11.59Fe-1.19Mn alloy. Intermetallics. 18(8), 1617-1622. https://doi.org/10.1016/j.intermet.2010.04.014.
[8] Belov, N.A., Aksenov, A.A. & Eskin, D.G. (2002). Iron in aluminum alloys. Impurity and Alloying Element (1st ed.). New York: Taylor & Francis Inc.
[9] Liu, G., Gong, M., Xie, D. & Wang, J. (2019). Structures and mechanical properties of Al-Al2Cu interfaces. The Journal of The Minerals, Metals & Materials Society. 71, 1200-1208. DOI: 10.1007/s11837-019-03333.
[10] Hurtalowa, L., Tillova, E. & Chalupova, M. (2012). Identyfication and analysis of intermetallic phases in age-hardened recycled AlSi9Cu3 alloy. Archive of Mechanical Engineering. LIX(4), 385-393. DOI: 10.2478/v10180-012-0020-3.
[11] Lu, L. & Dahle, A.K. (2005). Iron-rich intermetallic phases and their role in casting defect formation in hypoeutectic Al-Si alloys. Metallurgical and Mechanical Transactions. 36A, 819-835. https://doi.org/10.1007/s11661-005-1012-4.
[12] Xiao, F., Li, L., Zhou, R., Li, Y., Jiang, Y., Lu & D. (2018). Effect of melt treatment on Fe-rich phase in Al-25Si-2Fe-2Mn alloy. Advances in Materials Processing. 865-879. DOI: 10.1007/978-981-13-0107-0_85.
[13] Piątkowski, J. (2020). The crystallization of the AlSi9 alloy designed for the alfin processing of ring supports in engine pistons. Archives of Foundry Engineering. 20(2), 65-70. DOI 10.24425/afe.2020.131304.
