Improvement of the interdependence analytical model through selection of interfacial growth rates during the initial transient

Prasad, Arvind, Yuan, Lang, Lee, Peter D. and StJohn, David H. (2013). Improvement of the interdependence analytical model through selection of interfacial growth rates during the initial transient. In: Ian Stone, Brian McKay and Zhongyun Fan, Light Metals Technology 2013. LMT 2013: 6th International Light Metals Technology Conference, Old Windsor, UK, (77-81). 24-26 July, 2013. doi:10.4028/www.scientific.net/MSF.765.77

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Author Prasad, Arvind
Yuan, Lang
Lee, Peter D.
StJohn, David H.
Title of paper Improvement of the interdependence analytical model through selection of interfacial growth rates during the initial transient
Conference name LMT 2013: 6th International Light Metals Technology Conference
Conference location Old Windsor, UK
Conference dates 24-26 July, 2013
Proceedings title Light Metals Technology 2013   Check publisher's open access policy
Journal name Materials Science Forum   Check publisher's open access policy
Place of Publication Stafa-Zurich, Switzerland
Publisher Trans Tech Publications
Publication Year 2013
Year available 2013
Sub-type Fully published paper
DOI 10.4028/www.scientific.net/MSF.765.77
Open Access Status Not yet assessed
ISBN 9783037857663
9783038261476
9783037955017
ISSN 0255-5476
1662-9752
Editor Ian Stone
Brian McKay
Zhongyun Fan
Volume 765
Start page 77
End page 81
Total pages 5
Chapter number 2
Language eng
Abstract/Summary The Interdependence Theory is based on the concept that grain refinement of an alloy during the initial transient of solidification is governed by the simultaneous occurrence of growth of an already nucleated grain and the associated Constitutional Supercooling (CS) developing ahead of the growing grain. Nucleation of a new grain occurs when the maximum CS attained at the end of the diffusion field of the solute rejected in front of the growing grain, is larger than the nucleation undercooling Delta T-n of an inoculant particle present ahead of this point. The amount of grain growth plus the length of the diffusion field constitute the Nucleation-Free Zone (NFZ). The mathematical form of this theory is an analytical model which has been shown to be sensitive to the value of the growth rate nu of the solid-liquid interface chosen to predict the as-cast grain size. This work presents the development and application of a varying growth rate expression rather than a constant growth rate used in the analytical model to improve its agreement with mu MatIC, a numerical model of solidification which has been shown to effectively model grain growth and the evolution of the diffusion field. The possible range of values of growth rate that occurs during initial growth of a grain is obtained from numerical simulations. The resulting modified analytical model is compared against the numerical model for assessing the extent of NFZ formed.
Formatted Abstract/Summary
The Interdependence Theory is based on the concept that grain refinement of an alloy during the initial transient of solidification is governed by the simultaneous occurrence of growth of an already nucleated grain and the associated Constitutional Supercooling (CS) developing ahead of the growing grain. Nucleation of a new grain occurs when the maximum CS attained at the end of the diffusion field of the solute rejected in front of the growing grain, is larger than the nucleation undercooling ΔTn of an inoculant particle present ahead of this point. The amount of grain growth plus the length of the diffusion field constitute the Nucleation-Free Zone (NFZ). The mathematical form of this theory is an analytical model which has been shown to be sensitive to the value of the growth rate  of the solid-liquid interface chosen to predict the as-cast grain size. This work presents the development and application of a varying growth rate expression rather than a constant growth rate used in the analytical model to improve its agreement with μMatIC, a numerical model of solidification which has been shown to effectively model grain growth and the evolution of the diffusion field. The possible range of values of growth rate that occurs during initial growth of a grain is obtained from numerical simulations. The resulting modified analytical model is compared against the numerical model for assessing the extent of NFZ formed.
Keyword Grain refinement
Growth rate
Interdependence theory
Nucleation free zone (NFZ)
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID EP/I02249X/1
DP120101672
FP7-NMP3-LA-2012-280421
Institutional Status UQ

Document type: Conference Paper
Sub-type: Light Metals Technology 2013
Collections: School of Mechanical & Mining Engineering Publications
Official 2014 Collection
 
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Created: Tue, 29 Oct 2013, 20:42:36 EST by Katie Gollschewski on behalf of School of Mechanical and Mining Engineering