Microstructural evolution of iron-rich intermetallic compounds in scandium modified Al-7Si-0.3Mg alloys
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Author list: Chanyathunyaroj K., Patakham U., Kou S., Limmaneevichitr C.
Publisher: Elsevier
Publication year: 2017
Journal: Journal of Alloys and Compounds (0925-8388)
Volume number: 692
Start page: 865
End page: 875
Number of pages: 11
ISSN: 0925-8388
eISSN: 1873-4669
Languages: English-Great Britain (EN-GB)
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Abstract
Aluminum (Al) alloys usually have iron (Fe) as a common impurity, which has a very low solid solubility in Al and thus forms Fe-rich intermetallic compounds. Some types of Fe-rich intermetallic compounds are very harmful to mechanical properties. In this work, the microstructural evolution of the Fe-rich intermetallic compounds in scandium (Sc) modified Al-Si-Mg alloys was studied. There were two levels of Fe addition (0.2 and 0.4 wt%) and three levels of Sc addition (0, 0.2 and 0.4 wt%). Interrupted solidification experiments were performed to study the formation of intermetallic compounds. It was found that Sc reduced the nucleation temperature, minimum temperature and growth temperature of eutectic during solidification. Sc changed the morphology of Fe-rich intermetallic compounds from the α phase and β phase to Sc_3 and Sc_4 phases, and the shape of these phases was less harmful than that of the β phase. Sc changed the formation of Fe-rich intermetallic compounds from L → α-Al8Fe2Si + Al and L + α-Al8Fe2Si → β-Al5FeSi + Al into L → β-Al5FeSi + Al and L → β-Al5FeSi + Al + Si. Moreover, Sc changed the nucleation site of intermetallic compounds, causing the intermetallic compounds to solidify from the mold wall toward the mold center. © 2016 Elsevier B.V.
Keywords
Fe-rich intermetallic compounds
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