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Quantitative determination of zero-gravity effects on electronic materials processing germanium crystal growth with simultaneous interface demarcation. Experiment MA-060Experiment MA-060 was designed to establish the crystal growth and segregation characteristics of a melt in a directional solidification configuration under near zero-g conditions. The interface demarcation technique was incorporated into the experiment since it constitutes a unique tool for recording the morphology of the growth rate throughout solidification, and for establishing an absolute time reference framework for all stages of the solidification process. An extensive study was performed of the germanium crystals grown during the Apollo-Soyuz Test Project mission. It was found that single crystal growth was achieved and that the interface demarcation functioned successfully. There was no indication that convection driven by thermal or surface tension gradients was present in the melt. The gallium segregation, in the absence of gravity, was found to be fundamentally different in its initial and its subsequent stages from that of the ground-based tests. None of the existing theoretical models for growth and segregation can account for the observed segregation behavior in the absence of gravity.
Document ID
19770012182
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Gatos, H. C.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Witt, A. F.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1977
Publication Information
Publication: NASA. Marshall Space Flight Center Apollo-Soyuz Test Project
Subject Category
Astronautics (General)
Accession Number
77N19126
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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