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Nanostructural Fluctuation in Radiation-Amorphized Alloys

Published online by Cambridge University Press:  01 February 2011

Seiichi Watanabe
Affiliation:
Materials Science and Engineering, Hokkaido University, Sapporo 060–8628, Japan
Heishichirou Takahashi
Affiliation:
CARET, Hokkaido University, Sapporo 060–8628, Japan
Nghi Q. Lam
Affiliation:
Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA.
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Abstract

Spatio-temporal nanostructural fluctuations brought about by transient, metastable atom-cluster formation and the manifold nature of inherent atomic ordering in electron-irradiation-amorphized NiTi were investigated by using a combination of in situ observations inside a high-resolution high-voltage electron microscope (HR-HVEM) and image analyses of molecular-dynamics-simulated atom configurations. Nanometer-sized clusters were found to appear and disappear in the irradiated region. The random formation and annihilation of such nanoclusters are believed to be responsible for nanostructural fluctuations which appear to be related to transitions among manifold inherent structural states, involving multirelaxation processes. Temporal fluctuations in the amorphized structure were manifested through the dose-dependent local amorphization parameter, potential energy, volume, and inherent cluster bonding. The observed fluctuations obey a universal power law. Within the framework of the multi-Lorentzian picture, the resultant power law describes the distribution of multirelaxation times or cluster lifetimes. In addition, a unified relation for the temporal autocorrelation function for such fluctuation phenomena has been determined.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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References

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