Eutectic nucleation and growth in hypoeutectic Al-SI alloys at different strontium levels

Dahle, A. K., Nogita, K., Zindel, J. W., McDonald, S. D. and Hogan, L. M. (2001) Eutectic nucleation and growth in hypoeutectic Al-SI alloys at different strontium levels. Metallurgical and Materials Transactions A - Physical Metallurgy and Materials Science 35A, 32 4: 949-960. doi:10.1007/s11661-001-0352-y


Author Dahle, A. K.
Nogita, K.
Zindel, J. W.
McDonald, S. D.
Hogan, L. M.
Title Eutectic nucleation and growth in hypoeutectic Al-SI alloys at different strontium levels
Journal name Metallurgical and Materials Transactions A - Physical Metallurgy and Materials Science 35A   Check publisher's open access policy
ISSN 1073-5623
1543-1940
Publication date 2001-04-01
Sub-type Article (original research)
DOI 10.1007/s11661-001-0352-y
Open Access Status Not yet assessed
Volume 32
Issue 4
Start page 949
End page 960
Total pages 12
Place of publication New York, NY, United States
Publisher Springer New York
Language eng
Subject 091207 Metals and Alloy Materials
Abstract The effects of different levels of strontium on nucleation and growth of the eutectic in a commercial hypoeutectic Al-Si foundry alloy have been investigated by optical microscopy and electron backscattering diffraction (EBSD) mapping by scanning electron microscopy (SEM). The microstructural evolution of each specimen during solidification was studied by a quenching technique at different temperatures and Sr contents. By comparing the orientation of the aluminum in the eutectic to that of the surrounding primary aluminum dendrites by EBSD, the eutectic formation mechanism could be determined. The results of these studies show that the eutectic nucleation mode, and subsequent growth mode, is strongly dependent on Sr level. Three distinctly different eutectic growth modes were found, in isolation or sometimes together, but different for each Sr content. At very low Sr contents, the eutectic nucleated and grew from the primary phase. Increasing the Sr level to between 70 and 110 ppm resulted in nucleation of independent eutectic grains with no relation to the primary dendrites. At a Sr level of 500 ppm, the eutectic again nucleated on and grew from the primary phase while a well-modified eutectic structure was still present. A slight dependency of eutectic growth radially from the mold wall opposite the thermal gradient was observed in all specimens in the early stages of eutectic solidification.
Keyword Materials Science, Multidisciplinary
Metallurgy & Metallurgical Engineering
Silicon Alloys
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mechanical & Mining Engineering Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 143 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 13 Aug 2007, 22:16:59 EST