Microstructural evolution and mechanical properties of Al-7Si-0.3Mg alloys with erbium additions

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Author listPandee P., Patakham U., Limmaneevichitr C.

PublisherElsevier

Publication year2017

JournalJournal of Alloys and Compounds (0925-8388)

Volume number728

Start page844

End page853

Number of pages10

ISSN0925-8388

eISSN1873-4669

URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85029104156&doi=10.1016%2fj.jallcom.2017.09.054&partnerID=40&md5=68c620e8de25083e7ce2ad3fc3a92e05

LanguagesEnglish-Great Britain (EN-GB)


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Abstract

The mechanical properties of hypoeutectic Al-Si foundry alloys are generally controlled by their microstructures. The present study was performed to determine the influence of erbium (Er) in Al-7Si-0.3Mg alloys on the microstructures and mechanical properties. The evolution of microstructure was studied by thermal analysis and interrupted solidification technique. Optical microscopy, scanning electron microscope, and energy-dispersive X-ray were employed to characterize the alloy microstructures. The results demonstrated that the addition of Er significantly refined both the secondary dendrite arm spacing (SDAS) and the primary α-Al grain. Simultaneously, Er modified eutectic Si phase from coarse acicular plate-like structures into fine fibrous features. We observed that Er additions strongly suppress the nucleation of eutectic Si due to the preferential formation of ErP instead of AlP. Er additions change the eutectic growth mode from nucleation and growth on AlP particles to the propagation of a defined eutectic front from the mold walls. Moreover, Er addition that was cast for different holding times indicated that there was no fading effect on the SDAS, primary α-Al grain size, and eutectic Si morphology. Importantly, the tensile properties of the Er-modified alloys at as-cast and T6 conditions can be enhanced due to simultaneous refinement both the SDAS and the α-Al grains and modification of the eutectic Si. © 2017 Elsevier B.V.


Keywords

Eutectic solidificationSecondary dendrite arm spacing


Last updated on 2023-15-10 at 07:36