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Influence of convection on eutectic microstructureWhen the MnBi-Bi eutectic is directionally solidified, it forms fibers of MnBi in a matrix of bismuth. When the material solidified in space at rates of 30 and 50 cm/hr, the average fiber spacing lambda was about one half of the value obtained in cases in which the same material solidified on earth. Neither an altered temperature gradient nor a fluctuating freezing rate are apparently responsible for the change in lambda, and the possibility is studied that natural convection increases lambda on earth by perturbing the compositional field in the melt ahead of the growing solid. A theoretical analysis is conducted along with some experiments. On the basis of the theoretical results for lamellar growth, it is concluded that the spacing lambda increases with increasing stirring, especially at small freezing rates. The experiments indicate that at low growth rates the cross-sectional area of the MnBi blades increases with increased stirring and with decreased growth rate.
Document ID
19860052319
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Baskaran, V.
(Clarkson Coll. of Technology Potsdam, NY, United States)
Eisa, G. F.
(Clarkson Coll. of Technology Potsdam, NY, United States)
Wilcox, W. R.
(Clarkson College of Technology Potsdam, NY, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1985
Subject Category
Metallic Materials
Accession Number
86A37057
Funding Number(s)
CONTRACT_GRANT: NAS8-34887
Distribution Limits
Public
Copyright
Other

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