NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Microstructure and Macrosegregation Study of Directionally Solidified Al-7Si Samples Processed Terrestrially and Aboard the International Space StationThis talk reports research that has been carried out under the aegis of NASA as part of a collaboration between ESA and NASA for solidification experiments on the International Space Station (ISS). The focus has been on the effect of convection on the microstructural evolution and macrosegregation in hypoeutectic Al‐Si alloys during directional solidification (DS). The DS‐experiments have been carried out under 1‐g at Cleveland State University (CSU) and under low‐g on the International Space Station (ISS). The thermal processing‐history of the experiments is well defined for both the terrestrially‐processed samples and the ISS‐processed samples. We have observed that the primary dendrite arm spacings of two samples grown in the low‐g environment of the ISS show good agreement with a dendrite‐growth model based on diffusion controlled growth. The gravity‐driven convection (i.e., thermosolutal convection) in terrestrially grown samples has the effect of decreasing the primary dendrite arm spacings and causes macrosgregation. In order to process DS‐samples aboard the ISS, dendritic‐seed crystals have to partially remelted in a stationary thermal gradient before the DS is carried out. Microstructural changes and macrosegregation effects during this period are described.
Document ID
20140016705
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Angart, Samuel
(Arizona Univ. Tucson, AZ, United States)
Erdman, R. G.
(Arizona Univ. Tucson, AZ, United States)
Poirier, David R.
(Arizona Univ. Tucson, AZ, United States)
Tewari, S.N.
(Cleveland State Univ. Cleveland, OH, United States)
Grugel, R. N.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
November 26, 2014
Publication Date
October 5, 2014
Subject Category
Space Processing
Report/Patent Number
M14-3891
Meeting Information
Meeting: Investment Casting Institute Technical Conference & Equipment Expo
Location: Covington, KY
Country: United States
Start Date: October 5, 2014
End Date: October 8, 2014
Sponsors: Investment Casting Institute
Distribution Limits
Public
Copyright
Public Use Permitted.
No Preview Available