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Effects of Geometric Constraint on Phase Selection and Segregation in Cast TiAl

Published online by Cambridge University Press:  04 February 2011

Sailei Zhang ,
David R. Johnson  and
Matthew J.M. Krane
Sailei Zhang
Affiliation:
School of Materials Engineering, Purdue University, West Lafayette, IN 47906, U.S.A.
David R. Johnson
Affiliation:
School of Materials Engineering, Purdue University, West Lafayette, IN 47906, U.S.A.
Matthew J.M. Krane
Affiliation:
School of Materials Engineering, Purdue University, West Lafayette, IN 47906, U.S.A.
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Abstract

Simulations of directional solidification of binary peritectic TiAl alloys through ceramic preforms consisting of narrow straight channels with spacings on the order of the dendritic tip radius were performed with a modified cellular automaton coupled to a finite volume calculation of solute diffusion. Depending upon the channel spacing, the microstructure may be refined after dendritic growth through the preform. As the channel width decreases, the lateral solute diffusion in the liquid is more constrained, changing the morphology of the primary phase from dendritic to cellular. In narrow channels, the liquid concentration gradient ahead of the solid/liquid interface decreases resulted in lower growth velocities and higher undercoolings. For hypo-peritectic TiAl alloys, growth conditions that lead to growth of β dendrites can result in α nucleation and growth in narrow channels due to the geometric constraint on solute diffusion.

Keywords

crystal growthmicrostructurealloy
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1295: Symposium N – Intermetallic-Based Alloys for Structural and Functional Applications , 2011 , mrsf10-1295-n05-14
Copyright
Copyright © Materials Research Society 2011

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References

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