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The Early Stages of Solid-State Reactions in Ti/Al Multilayer Films

Published online by Cambridge University Press:  21 February 2011

C. Michaelsen
Affiliation:
GKSS Research Center, Institute for Materials Research, 21502 Geesthacht, Germany
S. WÖHlert
Affiliation:
GKSS Research Center, Institute for Materials Research, 21502 Geesthacht, Germany
R. Bormann
Affiliation:
GKSS Research Center, Institute for Materials Research, 21502 Geesthacht, Germany
K. Barmak
Affiliation:
Lehigh University, Department of Materials Science and Engineering, Bethlehem, PA 18015
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Abstract

We have investigated the solid-state reaction of Ti/Al multilayer films by x-ray diffraction (XRD) and differential scanning calorimetry (DSC), with focus on the early stages of the reaction provided by samples with pair thicknesses in the range 5 - 40 nm. This reaction, which results in formation of TiAl3 with metastable Ll2 structure, can be modeled by a nucleation and growth process on the basis of the Johnson-Mehl-Avrami theory, with a reaction-order parameter n ≈1. These observations indicate the significance of nucleation barriers even at early stages of solid-state reactions, and suggests that the phenomena of phase selection and formation of metastable phases can result from the presence of nucleation barriers.

Type
Research Article
Copyright
Copyright © Materials Research Society 1998

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References

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