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Microstructural Analysis of Rapid Solidification and Undercooling in the Al-Ge System

Published online by Cambridge University Press:  21 February 2011

M.J. Kaufman  and
H.L. Fraser
M.J. Kaufman
Affiliation:
Department of Metallurgy and the Materials Research LaboratoryUniversity of IllinoisUrbana, IL 61801
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Abstract

Submicron powders, amorphous films and melt spun ribbons of various Al-Ge alloys have been analyzed to determine the relative roles of undercooling and cooling rate in the production of non-equilibrium structures. All analyses were performed in transmission electron microscopes equipped with energy dispersive x-ray spectrometers. The submicron powders, produced by electro-hydrodynamic atomization, were analyzed in their as-received condition and then annealed and/or melted using the electron beam as a local heating source. Once molten, the liquid droplets were undercooled at different cooling rates by varying the rate of beam obstruction. In this manner, a number of different microstructures were produced. These included metastable crystalline phases and mixed amorphous/crystalline structures. By combining this technique with a microscope heating stage, it was possible to carry out controlled dynamic undercooling experiments and determine phase selection as a function of undercooling and composition. The amorphous films were rapidly heated with the electron beam in the microscope and metastable as well as stable phases were produced. The results of these complementary analyses will be compared and discussed with reference to current models and theories of rapid solidification.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 28: Symposium F – Rapidly Solidified Metastable Materials , 1983 , 335
Copyright
Copyright © Materials Research Society 1984

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References

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