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Bridgman Growth of GeSi Alloys in a Static Magnetic FieldGe(0.95)Si(0.050 alloy crystals have been grown by the vertical Bridgman technique, both with and without an axial 5 Tesla magnetic field. The crystals were processed in a constant axial thermal gradient and the effects of graphite, hot pressed boron nitride, and pyrolitic boron nitride ampoule materials on interface shapes and macrosegregation profiles were investigated. The sample grown in a graphite ampoule at 5 Tesla exhibited a macroscopic axial concentration profile close to that of complete mixing and strong striation patterns. In samples grown in boron nitride ampoules, both with and without a 5 Tesla magnetic field applied, measured macroscopic axial concentration profiles were intermediate between those expected for a completely mixed melt and diffusion-controlled growth, and striation patterns were also observed. Possible explanations for the apparent inability of the magnetic field to reduce the flow velocities to below the growth velocities are discussed, and results of growth experiments in pyrolitic boron nitride ampoules are also described.
Document ID
19990104336
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Volz, M. P.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Szofran, F. R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Vujisic, L.
(Cape Simulations, Inc. Wellesley, MA United States)
Motakef, S.
(Cape Simulations, Inc. Wellesley, MA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Subject Category
Metallic Materials
Meeting Information
Meeting: Crystal Growth
Location: Jerusalem
Country: Israel
Start Date: July 26, 1998
End Date: July 31, 1998
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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