Directional solidification in immiscible systems: The influence of gravity

Abstract

To take maximum advantage of immiscible alloys for proposed applications, it is desirable to produce aligned fibrous composite microstructures which contain a high volume fraction of the immiscible phase, L 2 /1–4/. Production of these microstructures should be possible through the directional solidification of hypermonotectic alloys. Analysis indicates that convection which may result from density differences in the melt will make cooperative growth of the fibrous structure in a hypermonotectic alloy very difficult under one-g conditions. Results from one-g experimentation support this conclusion /1,4–6/. However, results from directional solidification experiments aboard NASA's KC-135 zero-g aircraft and from transparent model systems indicate fibrous composite formation may indeed be possible in hypermonotectic alloys. /7/. Long duration low-g experimentation appears to be warranted in this area.