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The volume change during solidificationThe liquid-solid phase transformation of solidifying metallic melts is accompanied by a volume change Delta-Vm. This volume change produces a gravity-independent microscopic flow near the solidification front. In a ground-based laboratory, solidification processes are also affected by convection due to temperature and concentration gradients. A quantitative evaluation of the effects of these flows on the formation of structure requires reproducible values of Delta-Vm. Alloys with Delta-Vm = 0 would be best suited for such an evaluation, while alloys with a constant value for Delta-Vm are still usable. Another requirement is related to a solidus-liquidus interval which is as small as possible. One-phase alloys, which would be particularly well suited, could not be found. For these reasons, alloys which solidify in two phases, as for example eutectics, have been considered, taking into account the Al-Ge system. Attention is given to the volume change at the melting point, the measurement of this change, the volume change at solidification, and applications to terrestrial technology.
Document ID
19850015932
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Rittich, M. (NASA Headquarters Washington, DC United States)
Date Acquired
September 5, 2013
Publication Date
March 1, 1985
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NASA-TM-77817
NAS 1.15:77817
Meeting Information
Meeting: Spacelab Utilization: Mater. Res. and Technol. in Space; Seminar on Current Status
Location: Bonn
Country: Germany
Start Date: October 4, 1982
End Date: October 6, 1982
Accession Number
85N24243
Funding Number(s)
CONTRACT_GRANT: NASW-4004
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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