Sun, X. and Schneider, S. and Geyer, U. and Johnson, W. L. and Nicolet, M-A. (1996) Oxidation and crystallization of an amorphous Zr60Al15Ni25 alloy. Journal of Materials Research, 11 (11). pp. 2738-2743. ISSN 0884-2914. http://resolver.caltech.edu/CaltechAUTHORS:SUNjmr96
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The amorphous ternary metallic alloy Zr60Al15Ni25 was oxidized in dry oxygen in the temperature range 310 ±C to 410 ±C. Rutherford backscattering (RBS) and cross-sectional transmission electron microscopy (TEM) studies suggest that during this treatment an amorphous layer of zirconium-aluminum-oxide is formed at the surface. Nickel was depleted in the oxide and enriched in the amorphous alloy near the interface. The oxide layer thickness grows parabolically with annealing duration, with a transport constant of 2.8 x 10^-5 m^2/s x exp(-1.7 eV/kT). The oxidation rate may be controlled by the diffusion of Ni in the amorphous alloy. At later stages of the oxidation process, precipitates of nanocrystalline ZrO2 appear in the oxide near the interface. Finally, two intermetallic phases nucleate and grow simultaneously in the alloy, one at the interface and one within the alloy. An explanation involving preferential oxidation is proposed.
|Additional Information:||© 2005, Materials Research Society (Received 23 January, 1995; accepted 5 June, 1996) We gratefully acknowledge Professor T. Tombrello for providing access to the tandem accelerator for the 6.2 MeV 4He2+ backscattering spectrometry. We thank C. Garland for technical help on the transmission electron microscopy. Financial support for this work was provided by the United States Department of Energy (No. DEFG-03-86ER45242) and by the Army Research Office. Technical assistance by R. Gorris, M. Easterbrook, and A. Rice is also acknowledged.|
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