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Annealing-Induced Solid-State Amorphization and Nanocrystallization in Metallic Thin Films

Jinn P. Chu 1T. Mahalingam 1,2Chang-Ting Lo 1

1. National Taiwan Ocean University, Institute of Materials Engineering (NTOU), No. 2, Pei-Ning Road, Keelung 20224, Taiwan
2. Department of Physics, Alagappa University,, Karaikudi 630 003, India

Abstract

We present a direct experimental evidence that the controllable solid-state amorphization and nanocrystallization during annealing of a metastable film could serve as a precursor for exciting new nano materials. Unlike other metallic glassy materials that exhibit devitrification during annealing, our sputter deposited film with good glass-forming ability is transformed into various nano-scale and amorphous structures due to annealing process. Upon low-temperature annealing, a metastable crystalline phase that is formed due to the non-equilibrium sputtering re-dissolves. The new interesting discovery is that the metastable phase in the form of nanocrystalline is further transformed into another metastable phase in the amorphous state, instead of a crystalline state in the supercooled liquid region, with a subsequent crystallization at higher temperatures. The measured film properties (hardness and electrical resistivity) are in good agreement with those derived from the microstructure/crystal structure evolution. Such a structural development provides the opportunity to adjust the structure/property relationships necessary to tailor specific optical, electrical, and mechanical properties. The exceptional amorphization behavior can be rationalized as a consequence of the low free energy of amorphous phases, with combined effects of thermal and interfacial energies between the nanocrystalline and amorphous phases.

 

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Presentation: oral at E-MRS Fall Meeting 2004, Symposium I, by Jinn P. Chu
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-19 18:45
Revised:   2009-06-08 12:55