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An electron microscopic study of a rapidly solidified Al-5 wt. % Co alloy

Published online by Cambridge University Press:  31 January 2011

G. Van Tendeloo ,
Jyothi Menon  and
C. Suryanarayana
G. Van Tendeloo
Affiliation:
University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
Jyothi Menon
Affiliation:
Centre of Advanced Study in Metallurgy, Banaras Hindu University, Varanasi-221 005, India
C. Suryanarayana
Affiliation:
Centre of Advanced Study in Metallurgy, Banaras Hindu University, Varanasi-221 005, India
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Abstract

An Al-5 wt. % Co alloy has been rapidly solidified from the liquid state, resulting in the formation of a slightly supersaturated aluminum solid solution and the monoclinic Al9Co2 phase. High-resolution electron microscopy and electron diffraction have been extensively employed to characterize the as-solidified as well as the annealed foils. The high-resolution micrographs of the as-solidified solid solution showed the presence of clustering and D 1a - type ordering on an extremely small microscopic scale. Annealing at temperatures above 623 K resulted in the precipitation of Al9Co2 in the form of platelets arranged in a Widmanstätten pattern. Orientation relationships between the Al9Co2 platelets and the matrix have been established. Guinier-Preston zonelike platelets on close-packed {111} planes, however, have also been observed upon electron irradiation in the annealed alloys, presumably due to the enhanced diffusivity of cobalt atoms.

Type
Articles
Information
Journal of Materials Research , Volume 2 , Issue 5 , October 1987 , pp. 547 - 556
Copyright
Copyright © Materials Research Society 1987

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References

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