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Microstructural transitions during containerless processing of undercooled Fe-Ni alloysIn order to identify the possible hierarchy of microstructural pathways and transitions, a systematic evaluation of the microstructural evolution in undercooled Fe-Ni alloys was performed on uniformly processed samples covering seven orders of magnitude in volume. At appropriate undercooling levels, alternate solidification pathways become thermodynamically possible and metastable product structures can result from the operation of competitive solidification kinetics. For thermal history evaluation, a heat flow analysis was applied and tested with large Fe-Ni alloy particles (1 to 3 mm) to assess undercooling potential. Alloy powders (10 to 150 microns), with large liquid undercoolings, were studied under the same composition and processing conditions to evaluate the solidification kinetics and microstructural evolution, including fcc/bcc phase selection and the thermal stability of a retained metastable bcc phase. The identification of microstructural transitions with controlled variations in sample size and composition during containerless solidification processing was used to develop a microstructure map which delineates regimes of structural evolutions and provides a unified analysis of experimental observations in the Fe-Ni system.
Document ID
19940036495
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Thoma, D. J.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Perepezko, J. H.
(Wisconsin Univ. Madison, United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1992
Publication Information
Publication: Metallurgical Transactions A - Physical Metallurgy and Materials Science
ISSN: 0360-2133
Subject Category
Materials Processing
Accession Number
94A13150
Funding Number(s)
CONTRACT_GRANT: DAAL03-90-G-0042
CONTRACT_GRANT: NAG8-771
Distribution Limits
Public
Copyright
Other

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