A solidification model for unmodified, Na-modified and Sr-modified Al-Si alloys

Publication: Research - peer-reviewArticle in proceedings – Annual report year: 2012

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An addition of small amounts of Na and Sr is commonly used in the industry to modify the eutectic in Al-Si alloys. Both Na and Sr suppress nucleation of the eutectic forcing nucleation and growth to take place at higher undercooling than in the unmodified material. Thus the scale of the eutectic and the shape of the Si crystals are modified to a fine fibrous form so that the ductility of the material is increased. In the present work a one-dimensional numerical model is proposed that describes nucleation and growth of both primary dendrites and eutectic grains as a function of cooling conditions and modification. The model assumes that dendrites nucleate easily when the liquidus temperature is reached and that they grow as heat is extracted by the mould. Nucleation of the eutectic grains depends on local undercooling and growth is governed by a balance between growth of the eutectic grains and the rate at which heat is extracted by the mould. Experimental data is used to determine constants in the nucleation function. It is shown how cooling conditions and mode of modification influence nucleation and growth conditions.
Original languageEnglish
TitleThe 3rd International Conference on Advances in Solidification Processes, Rolduc Abbey 2011
Number of pages7
PublisherIOP Publishing Ltd
Publication date2012
Pages012033
DOIs
StatePublished

Conference

ConferenceICASP-3
CountryNetherlands
CityKerkrade
Period07/06/1110/06/11
NameIOP Conference Series: Materials Science and Engineering
Volume27
ISSN (Print)1757-899x
CitationsWeb of Science® Times Cited: 0

Keywords

  • MATERIALS, METALLURGY, PHYSICS, ALUMINUM-SILICON ALLOYS, EUTECTIC ALLOYS, TEMPERATURE
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