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Bulk Formation of Metallic Glasses and Amorphous Silicon from the MeltBy using metallic glass compositions with a high relative glass transition temperature, such as Pd40Ni40P20, homogeneous nucleation also becomes negligible. Large (5g) masses of this alloys were obtained using a molten B2O3 flux. Presently, bulk glass formation in iron based glasses is being investigated. It is expected that if an undercooling of about 250K can be achieved in a Ge or Si melt, formation of the amorphous semiconductor phase (rather than the crystal) may be kinetically favored. The volumetric behavior of undercooled liquid Ga droplet dispersion is investigated by dilatometry. A theoretical model (both analytical and numerical) was developed for transient nucleation in glass forming melts. The model, originally designed for isothermal conditions, was extended to continuous quenching. It is being applied to glass formation in various metallic and oxide systems. A further refinement will be the inclusion of diffusion controlled interfacial rearrangements governing the growth of the crystal embryos.
Document ID
19860000687
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Spaepen, F.
(Harvard Univ. Cambridge, MA, United States)
Date Acquired
August 12, 2013
Publication Date
May 1, 1985
Publication Information
Publication: NASA, Washington Microgravity Sci. and Appl. Program Tasks
Subject Category
Astronautics (General)
Accession Number
86N10154
Funding Number(s)
CONTRACT_GRANT: NAS8-35416
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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