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

Niels Skat Tiedje, Jesper Henri Hattel, J. A. Taylor, M. A. Easton

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

    Abstract

    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
    Title of host publicationThe 3rd International Conference on Advances in Solidification Processes, Rolduc Abbey 2011
    Number of pages7
    PublisherIOP Publishing
    Publication date2012
    Pages012033
    DOIs
    Publication statusPublished - 2012
    Event3rd International Conference on Advances in Solidification Processes - Rolduc Abbey, Aachen, Netherlands
    Duration: 7 Jun 201110 Jun 2011

    Conference

    Conference3rd International Conference on Advances in Solidification Processes
    LocationRolduc Abbey
    Country/TerritoryNetherlands
    CityAachen
    Period07/06/201110/06/2011
    SeriesI O P Conference Series: Materials Science and Engineering
    Volume27
    ISSN1757-8981

    Keywords

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

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