In-situ X-ray Video Microscopy Studies of Al-Si Eutectic Solidification

Mathiesen, Ragnvald H., Arnberg, Lars, Li, Yanjun and Dahle, Arne K. (2010). In-situ X-ray Video Microscopy Studies of Al-Si Eutectic Solidification. In: Shinji Kumai, Osamu Umezawa, Yoshimasa Takayama, Takayuki Tsuchida and Tatsuo Sato, Proceedings of the 12th International Conference on Aluminium Alloys. The 12th International Conference on Aluminium Alloys (ICAA12), Yokohama, Japan, (1267-1272). 5-9 September 2010.

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Author Mathiesen, Ragnvald H.
Arnberg, Lars
Li, Yanjun
Dahle, Arne K.
Title of paper In-situ X-ray Video Microscopy Studies of Al-Si Eutectic Solidification
Conference name The 12th International Conference on Aluminium Alloys (ICAA12)
Conference location Yokohama, Japan
Conference dates 5-9 September 2010
Proceedings title Proceedings of the 12th International Conference on Aluminium Alloys
Place of Publication Tokyo, Japan
Publisher The Japan Institute of Light Metals
Publication Year 2010
Sub-type Fully published paper
Editor Shinji Kumai
Osamu Umezawa
Yoshimasa Takayama
Takayuki Tsuchida
Tatsuo Sato
Start page 1267
End page 1272
Total pages 6
Language eng
Abstract/Summary In-situ studies of Al-Si eutectic growth has been carried out for the first time by X-ray video microscopy during directional solidification of Al-Si-Cu alloys with and without Sr-addtions. The unmodified eutectics showed distinctive non-isothermal growth dynamics, where Si-crystals attained needle-like tip morphologies and progressed under significantly higher undercooling than Al, leading to formation of an irregular eutectic with Si as the leading phase and subsequent nucleation of Al on the Si-surfaces. In the Sr-modified alloys, the eutectic reaction was found to be strongly suppressed, occurring with low nucleation frequencies at undercoolings in the range 10-18 K. In the Cu-enriched melt, the eutectic front was found to attain meso-scale interface perturbations evolving into equiaxed cellular rosettes in order to accommodate to the long-range redistribution of Cu from the composite eutectic interface. The eutectic front also attained short-range microscale interface perturbations consistent with characteristics of a fibrous Si growth, however further improvements in spatial resolution is required in order to study microscale structure formation in greater detail. Evidence was found in support of Si-nucleation occurring on potent particles suspended in the melt. Yet, both with Sr- modified and unmodified alloys, Si precipitation alone was not sufficient to facilitate the eutectic reaction, which apparently required additional undercooling for Al to form on the Si-particles. To what extent nucleation mechanisms in the Cu-enriched systems are transferable to binary or commercial Al-Si alloys remains uncertain.
Keyword Aluminium alloys
Al-Si eutectic solidification
Radiography
Q-Index Code E1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Conference Paper
Collection: School of Mechanical & Mining Engineering Publications
 
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Created: Wed, 23 Mar 2011, 14:17:12 EST by Sally Beard on behalf of School of Mechanical and Mining Engineering