Response of MnBi-Bi eutectic to freezing rate changesReference is made to a study by Fu and Wilcox (1981), which treated theoretically the influence on freezing rate of sudden changes in translation rate in the Bridgman-Stockbarger technique. This treatment is extended here to a linear ramped translation rate and an oscillatory freezing rate. It is found that oscillations above a few hertz are highly damped in small-diameter apparatus. An experimental test is carried out of the theoretical predictions for a sudden change of translation rate. The MnBi-Bi eutectic is solidified with current-induced interface demarcation. The experimental results accord reasonably well with theory if the silica ampoule wall is assumed to either (1) contribute only a resistance to heat exchange between the sample and the furnace wall or (2) transmit heat effectively in the axial direction by radiation. In an attempt to explain the fact that a finer microstructure is obtained in space, MnBi-Bi microstructure is determined when the freezing rate is increased or decreased rapidly. Preliminary results suggest that fiber branching does not occur as readily as fiber termination.
Document ID
19830062085
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Nair, M. (Clarkson Coll. of Technology Potsdam, NY, United States)
Fu, T.-W. (Clarkson Coll. of Technology Potsdam, NY, United States)
Wilcox, W. R. (Clarkson Coll. of Technology Potsdam, NY, United States)
Doddi, K. (Clarkson Coll. of Technology Potsdam, NY, United States)
Ravishankar, P. S. (Clarkson College of Technology Potsdam, NY, United States)
Larson, D. (Grumman Aerospace Corp. Bethpage, NY, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1982
Subject Category
Astronautics (General)
Meeting Information
Meeting: Materials processing in the reduced gravity environment of space; Annual Meeting