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

Tiedje, N, Hattel, J, Taylor, J and Easton, M 2011, 'A solidification model for unmodified, Na-modified and Sr-modified Al-Si alloys', IOP Conference Series: Materials Science and Engineering, vol. 27, pp. 1-6.


Document type: Journal Article
Collection: Journal Articles

Title A solidification model for unmodified, Na-modified and Sr-modified Al-Si alloys
Author(s) Tiedje, N
Hattel, J
Taylor, J
Easton, M
Year 2011
Journal name IOP Conference Series: Materials Science and Engineering
Volume number 27
Start page 1
End page 6
Total pages 6
Publisher Institute of Physics Publishing
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.
Subject Materials Engineering not elsewhere classified
Keyword(s) Al-Si alloy
Cooling conditions
Eutectic grains
Experimental data
Liquidus temperature
Nucleation and growth
Primary dendrite
Si crystals
Solidification models
DOI - identifier 10.1088/1757-899X/27/1/012033
Copyright notice © Copyright 2012 Elsevier B.V., All rights reserved.
ISSN 1757-8981
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