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Vertical solidification of dendritic binary alloysThree numerical techniques are employed to analyze the influence of thermosolutal convection on defect formation in directionally solidified (DS) alloys. The finite-element models are based on the Boussinesq approximation and include the plane-front model and two plane-front models incorporating special dendritic regions. In the second model the dendritic region has a time-independent volume fraction of liquid, and in the last model the dendritic region evolves as local conditions dictate. The finite-element models permit the description of nonlinear thermosolutal convection by treating the dendritic regions as porous media with variable porosities. The models are applied to lead-tin alloys including DS alloys, and severe segregation phenomena such as freckles and channels are found to develop in the DS alloys. The present calculations and the permeability functions selected are shown to predict behavior in the dendritic regions that qualitatively matches that observed experimentally.
Document ID
19920054938
Document Type
Reprint (Version printed in journal)
Authors
Heinrich, J. C.
(NASA Lewis Research Center Cleveland, OH, United States)
Felicelli, S.
(NASA Lewis Research Center Cleveland, OH, United States)
Poirier, D. R.
(Arizona, University Tucson, United States)
Date Acquired
August 15, 2013
Publication Date
August 1, 1991
Publication Information
Publication: Computer Methods in Applied Mechanics and Engineering
Volume: 89
Issue: 3-Jan
ISSN: 0045-7825
Subject Category
Solid-State Physics
Accession Number
92A37562
Funding Number(s)
CONTRACT_GRANT: NAG3-1060
CONTRACT_GRANT: NAG3-723
Distribution Limits
Public
Copyright
Other

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