Investigation on the Effect of Solidification Parameters on Microstructural Characteristics and Hardness of Al-Fe Alloy Produced by Directional Solidification in Bridgeman Furnace

Document Type : Original Research Article

Authors

1 School of Metallurgy and Material Engineering, Iran University of Science and Technology.

2 School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST)

3 M.Sc, School of Metallurgy and Material Engineering, Iran University of Science and Technology

Abstract

The aim of the present study is to produce an in-situ Al matrix composite reinforced by iron-bearing intermetallics. Therefore, the effects of solidification parameters such as solidification rate (RL‌) and cooling rate (T ̇) on the microstructural characteristics of a hypoeutectic Al-1.0%wtFe alloy during directional solidification have been investigated. The directional solidification process has been carried out using a Bridgman furnace having a water-cooled system at the bottom of the cold zone. The flow rate of the water was 1, 2 L.min-1 and the withdrawal velocity of the ingot was 1, 5, and 10 mm.min-1. Optical and electron scanning microscopy (SEM) have been used to study the microstructure of the samples. Cellular microstructure with the iron-intermetallic phases at the peripheral walls of the cells were found along the directional solidified samples. In order to characterize the intermetallic phases, the energy dispersive spectroscopy (EDS) was used. Cellular spacing (λc) was calculated in some sections from the bottom of chill zone. Variation of cellular spacing was plotted as a function of both solidification rate and distance from the bottom of chill zone. Hardness test was carried out on each cross-section and the hardness profile was plotted as a function of cellular spacing. The results showed that the hardness of Al-1.0%wt.Fe alloy was increased where the cellular spacing was reduced.

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[1] Allen C., Oreilly K., Cantor B., Evans P., Intermetallic phase selection in 1XXX Al alloys, Progress in Materials Science, 1998, 43(2) 89-170.
[2] Burden M., Jones H., A metallographic study of the effect of more rapid freezing on the cast structure of aluminum-iron alloys, Metallography, 1970, 3(3) 307-326.
[3] Mondolfo L. F., Structure and Properties of Aluminum Alloys, Metallurgiya, Moscow, 1979.
[4] Young R., Clyne T., An Al3Fe intermetallic phase formed during controlled solidification, Scripta Metallurgica, 1986, 11(1) 1211-1215.
[5] Chen X.G., Growth mechanisms of intermetallic phases in DC cast AA 1 XXX alloys (direct-chill), Light Metals, 1998, 1071-1076.
[6] Goulart P.R., Cruz K.S., Spinelli J.E., Ferreira I.L., Cheung N., Garcia A., Cellular growth during transient directional solidification of hypoeutectic Al–Fe alloys, Journal of Alloys and Compounds, 2009, 470(1) 589-599.
[7] Campbell J., Castings, Butterworth-Heinemann, 2003.
[8] Gündüz M., Kaya H., Cadırlı E., Maraşlı N., Keşlioğlu K, Saatçi B., Effect of solidification processing parameters on the cellular spacings in the Al–0.1%wtTi and Al–0.5%wtTi alloys, Journal of Alloys and Compounds, 2007, 439(1) 114-127.
[9] Rosa D.M., Spinelli J.E., Ferreira I.L., Garcia A., Cellular/dendritic transition and microstructure evolution during transient directional solidification of Pb-Sn alloys, Metallurgical and Materials Transactions A, 2008, 39(9) 2161-2174.
[10] Rocha O.L., Siqueira C.A., Garcia A., Cellular spacings in unsteady-state directionally solidified Sn–Pb alloys, Materials Science and Engineering A, 2003, 361(1) 111-118.
[11] Thomas T.R., Cama H., Evans P., Hunt J., editors, A study of the phases found in Al rich Al-Fe alloys, Proceedings of the 4th Decennial International Conference on Solidification Processing, 1997.
[12] اصغرزاده پ.، بررسی عوامل انجمادی بر مشخصات ریزساختار در انجماد جهت‌دار آلیاژ Al-Ni، پایان‌نامه کارشناسی ارشد؛ دانشگاه علم و صنعت ایران، 1394.
[13] قنبری حقیقی م.، شبیه‌سازی عددی و فیزیکی فرآیند انجماد جهت‌دار به روش بریجمن به منظور رشد تک بلور سوپرآلیاژ پایه نیکل، پایان‌نامه دکترا، دانشگاه علم و صنعت ایران، 1393.
[14] شادفر ف.، بررسی تأثیر پارامترهای انجمادی بر مشخصات ریزساختاری در انجماد جهت‌دار آلیاژ Al-Cu، پایان‌نامه کارشناسی ارشد؛ دانشگاه علم و صنعت ایران، 1392.
[15] Silva B.L., Garcia A., Spinelli J.E., The effects of microstructure and intermetallic phases of directionally solidified Al–Fe alloys on microhardness, Materials Letters, 2012, 89, 291-295.
[16] Goulart P.R., Lazarine V.B., Leal C.V., Spinelli J.E., Cheung N., Garcia A., Investigation of intermetallics in hypoeutectic Al–Fe alloys by dissolution of the Al matrix, Intermetallics, 2009, 17(9) 753-761.
[17] Goulart P., Spinelli J., Cheung N., Mangelinck-Nöel N, Garcia A., Al–Fe hypoeutectic alloys directionally solidified under steady-state and unsteady-state conditions, Journal of Alloys and Compounds, 2010, 504(1) 205-210.
[18] Cadirli E., Gündüz M., The dependence of lamellar spacing on growth rate and temperature gradient in the lead–tin eutectic alloy, Journal of Materials Processing Technology, 2000, 97(1) 74-81.
[19] Dong L., Jones H., The dependence of growth temperature on growth velocity for primary Al3Fe in steady state solidification of hypereutectic Al-Fe alloys, Scripta Metallurgica et Materialia, 1991, 25(12) 2855-2859.
[20] Coriell S.R., McFadden G.B., Sekerka R.F., Cellular Growth during directional solidification, Annual Review of Materials Science, 1985, 15(1) 119-145.
[21] Kaya H., Cadırlı E, Böyük U., Marasl N., Variation of microindentation hardness with solidification and microstructure parameters in the Al based alloys, Applied Surface Science, 2008, 255(5) 3071-3078.
[22] Kaya H., Gündüz M., Çadırlı E., Marasl N., Dependency of microindentation hardness on solidification processing parameters and cellular spacing in the directionally solidified Al based alloys, Journal of Alloys and Compounds, 2009, 478(1) 281-286.