Modification mechanism of eutectic silicon in Al-6Si-0.3Mg alloy with scandium

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Author listPatakham U., Kajornchaiyakul J., Limmaneevichitr C.

PublisherElsevier

Publication year2013

JournalJournal of Alloys and Compounds (0925-8388)

Volume number575

Start page273

End page284

Number of pages12

ISSN0925-8388

eISSN1873-4669

URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84879248373&doi=10.1016%2fj.jallcom.2013.05.139&partnerID=40&md5=4a70e199b745b51d1f3a058d78ecec64

LanguagesEnglish-Great Britain (EN-GB)


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Abstract

The modification mechanism of eutectic silicon in Al-6Si-0.3Mg alloy with scandium was studied. The crystallographic orientation relationships between primary dendrites and the eutectic phase of unmodified and modified Al-6Si-0.3 Mg alloys were determined using electron backscatter diffraction (EBSD). The orientation of aluminum modified with scandium in the eutectic phase was different from that of the neighboring primary dendrites. This result implies that eutectic aluminum grows epitaxially from the surrounding primary aluminum dendrites in the unmodified alloy and that eutectic aluminum grows competitively from the surrounding primary aluminum dendrites in the modified alloy. The pole figure maps of eutectic Si in the [100], [110] and [111] axes of the unmodified and Sc-modified alloys were different, suggesting that the eutectic Al and Si crystals in modified alloy growth are more isotropic and cover a larger set of directions. The lattice fringes of Si of the alloys with and without Sc modification were different in the TEM results. The lattice fringes of Si in modified alloy were found to be multiple twins. However, this was not observed in the unmodified alloy. The growth characteristic of eutectic Si crystal in modified alloy suggests the occurrence of multiple twinning reactions and the formation of a high density of twins. This modification mechanism by Sc is explained by the results of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis, which provide strong evidence of the occurrence of the impurity-induced twinning (IIT) mechanism. ฉ 2013 Elsevier B.V. All rights reserved.


Keywords

Hypoeutectic Al-Si-Mg alloyModification mechanismScandium


Last updated on 2023-13-10 at 07:35