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Segregation and grain refinement in cast titanium alloys

Published online by Cambridge University Press:  31 January 2011

M.J. Bermingham ,
S.D. McDonald ,
D.H. StJohn  and
M.S. Dargusch
M.J. Bermingham*
Affiliation:
CAST Cooperative Research Centre, School of Engineering, The University of Queensland, Brisbane, Queensland, Australia
S.D. McDonald
Affiliation:
CAST Cooperative Research Centre, School of Engineering, The University of Queensland, Brisbane, Queensland, Australia
D.H. StJohn
Affiliation:
CAST Cooperative Research Centre, School of Engineering, The University of Queensland, Brisbane, Queensland, Australia
M.S. Dargusch
Affiliation:
CAST Cooperative Research Centre, School of Engineering, The University of Queensland, Brisbane, Queensland, Australia
*
a) Address all correspondence to this author. e-mail: m.bermingham@uq.edu.au
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Abstract

The growth restriction factor is a parameter derived from binary phase diagrams and is a useful predictor for the grain refining response when a solute is added to a base alloy. This work investigates the relevance of growth restriction theory to titanium alloys where solidification rates are an order of magnitude faster than previous studies in aluminum- and magnesium-based systems. In particular, the segregation of Fe and Cr in titanium is investigated and the effects on grain size studied. It was found that the Scheil equation reasonably modeled solidification of titanium where cooling rates approach 120 °C/s, and the growth restriction factors for Fe and Cr were useful in predicting prior-β grain refinement. However, it was found that caution must be used when calculating growth restriction factors from binary phase diagrams.

Keywords

CastingGrain sizeTi
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 4 , April 2009 , pp. 1529 - 1535
Copyright
Copyright © Materials Research Society 2009

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