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A Thermodynamic Approach in Tuning Phase Stability in Nanocomposite Multilayers

Published online by Cambridge University Press:  01 February 2011

G. B. Thompson ,
R. Banerjee  and
H. L. Fraser
G. B. Thompson
Affiliation:
now at University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL 35487 The Ohio State University, Department of Materials Science and Engineering, Columbus, OH 43210
R. Banerjee
Affiliation:
The Ohio State University, Department of Materials Science and Engineering, Columbus, OH 43210
H. L. Fraser
Affiliation:
The Ohio State University, Department of Materials Science and Engineering, Columbus, OH 43210
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Abstract

Changes in the crystallographic phase stability of individual layers in a multilayered thin film stack are expected to have a significant influence upon the functional properties of the structure. The ability to predict and tune these phase stability states is of relevant importance in order to maximize the functional properties of the multilayer. A classical thermodynamic methodology, based upon competitive volumetric and interfacial free energies, has been used in the prediction and subsequent confirmation of the hcp to bcc phase stability in a Ti/Nb multilayer. An outcome of this model is a new type of phase stability diagram that can be used to predict the hcp Ti and bcc Ti phase stability as a function of length scale and volume fraction. The Ti layers were subsequently alloyed with a bcc-stabilizing element. The alloyed sputtered deposited Ti layers were able to stabilize the bcc Ti phase to a larger layer thickness as compared to the unalloyed Ti/Nb multilayers. The percentage of alloying element added to the Ti layer in controlling the critical transition thickness between the two phase states had good agreement with the predictions proposed by the thermodynamic model.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 788: Symposium L – Continuous Nanophase and Nanostructured Materials , 2003 , L3.40
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

[1] Thompson, G.B., Banerjee, R., Dregia, S.A., Miller, M.K., and Fraser, H.L. “Comparison of bcc phase stability in Zr/Nb and Ti/Nb thin film multilayers” scheduled press release Journal of Materials Research March (2004).Google Scholar
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