Particle engulfment and pushing by solidifying interfaces : Part II. Microgravity experiments and theoretical analysis

Results of the directional solidification (DS) experiments on particle engulfment and pushing by solidifying interfaces (PEP), conducted on the space shuttle Columbia during the Life and Microgravity Science (LMS) Mission, are reported. Two pure aluminum (99.999 pct) 9 mm cylindrical rods, loaded wi...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 1998-06, Vol.29 (6), p.1697-1706
Main Authors: STEFANESCU, D. M, JURETZKO, F. R, DHINDAW, B. K, CATALINA, A, SEN, S, CURRERI, P. A
Format: Article
Language:English
Subjects:
Aluminum
Applied sciences
Columbia (Orbiter)
Critical velocity
Cross-disciplinary physics: materials science
rheology
Directional solidification
Exact sciences and technology
Free convection
Materials science
Metals. Metallurgy
Microgravity
Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
Physics
Pushing
Solidification
Space shuttle
Surface energy
Velocity
Zirconium dioxide
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Summary:Results of the directional solidification (DS) experiments on particle engulfment and pushing by solidifying interfaces (PEP), conducted on the space shuttle Columbia during the Life and Microgravity Science (LMS) Mission, are reported. Two pure aluminum (99.999 pct) 9 mm cylindrical rods, loaded with about 2 vol pct 500µm-diameter zirconia particles, were melted and resolidified in the microgravity (µg) environment of the shuttle. One sample was processed at a stepwise increased solidification velocity and the other at a stepwise decreased velocity. It was found that a pushing/engulfment transition (PET) occurred in the velocity range of 0.5 to 1 µm/s. This is smaller than the ground PET velocity of 1.9 to 2.4 µm/s. This demonstrates that natural convection increases the critical velocity. A previously proposed analytical model for PEP was further developed. A major effort to identify and produce data for the surface energy of various interfaces required for calculation was undertaken. The predicted critical velocity for PET was 0.775 µm/s.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-998-0092-3