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Droplet Growth in Undercooled Cu-Co AlloysHigh undercooling usually leads to the refinement of microstructures, while an opposite tendency occurs in liquid immiscible alloys. In the Cu-Co system, there is a metastable liquid miscibility gap which may allow the study of droplet nucleation and growth by undercooling experiments. In the present work, two alloys of Cu50Co50 and Cu68Co32 (atomic) were undercooled using a melt fluxing technique in which the liquid separation temperature could be directly measured. It was observed that after separation the resultant melts were further undercooled by 315 K prior to solidification. The relationship between the largest droplet radius and undercooling was found to exhibit three regimes: a power law growth, linear growth, and saturation stage. In addition to dendrites and droplet-like morphology reported previously, an interconnected structure was formed for the Cu50Co50 alloy at intermediate undercooling. It played a crucial role in droplet coarsening at high undercooling.
Document ID
19990079438
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Robinson, Michael B.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Li, Delin
(NASA Marshall Space Flight Center Huntsville, AL United States)
Rathz, Thomas J.
(Alabama Univ. Huntsville, AL United States)
Williams, Gary A.
(Alabama Univ. Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Metallic Materials
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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