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Comparison of structures of gas atomized and of emulsified highly undercooled Ni-Sn alloy dropletsA comparison is made of microstructures of droplets of Ni-Sn alloys rapidly solidified by gas atomization and in a glass emulsifying medium. Cooling rate of the gas atomized particles ranged from 10 to the 3rd to 10 to the 6th K/s depending on droplet diameter (20-230 microns). In the hypoeutectic alloy studied, /Ni-(25 wt pct Sn)/, most particles showed a dendritic structure. These same particles, melted and resolidified in a glass medium using DTA (Differential Thermal Analysis), showed undercoolings up to 280 K: the structures were dendritic at low undercoolings and nondendritic at undercoolings above 220 K. It is concluded that the gas atomized particles exhibited little or no undercooling before nucleation; the solidification time of the undercooled emulsified droplets is substantially less than that of gas atomized droplets, and the undercooling required to achieve nondendritic structure depends on sample size.
Document ID
19870024774
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Yamamoto, M.
(Nippon Mining Co., Ltd. Tokyo, Japan)
Wu, Y.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Shiohara, Y.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Flemings, M. C.
(MIT Cambridge, MA, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1986
Subject Category
Metallic Materials
Accession Number
87A12048
Funding Number(s)
CONTRACT_GRANT: NSG-7645
Distribution Limits
Public
Copyright
Other

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