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Solidification of Undercooled Monotectic Alloys

Published online by Cambridge University Press:  15 February 2011

J. H. Perepezko ,
C. Galaup  and
K. P. Cooper
J. H. Perepezko
Affiliation:
University of Wisconsin-Madison, Department of Metallurgical and Mineral Engineering, 1509 University Avenue., Madison, WI 53706, U.S.A;
C. Galaup
Affiliation:
Centre de Recherches de Pont-à-Mousson, Maidieres 54700, Pont-à-Mousson, France.
K. P. Cooper
Affiliation:
University of Wisconsin-Madison, Department of Metallurgical and Mineral Engineering, 1509 University Avenue., Madison, WI 53706, U.S.A;
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Abstract

During the processing of monotectic alloys large compositional segregation of the liquid can precede final solidification. Under normal treatment a coarse scale phase distribution is obtained as a result of convection and sedimentation effects which may be minimized by microgravity processing. In undercooled droplets (5–20μ) of Bi-Ga alloys with compositions near the monotectic point, a finescale segregation has been observed and is similar to that formed during a microgravity treatment of bulk samples. Near the critical point of the miscibility gap, Bi-rich alloys exhibit an undercooling prior to phase separation, while in Ga-rich alloys the onset of phase separation is at the miscibility gap boundary. Similarly, in Cu-Pb alloys an undercooling below the miscibility gap prior to phase separation is observed for Cu-rich alloys, but not for Pb-rich alloys near the critical point. These observations are consistent with the operation of a critical point wetting behavior which can modify the liquid segregation pattern during microgravity treatment.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 9 , 1981 , 491
Copyright
Copyright © Materials Research Society 1982

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References

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