Waniuk, Theodore and Schroers, Jan and Johnson, William L. (2003) Timescales of crystallization and viscous flow of the bulk glass-forming Zr-Ti-Ni-Cu-Be alloys. Physical Review B, 67 (18). Art. No. 184203. ISSN 0163-1829 http://resolver.caltech.edu/CaltechAUTHORS:WANprb03a
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Crystallization behavior and equilibrium viscosity of a series of alloys in the Zr-Ti-Cu-Ni-Be system are studied using multiple techniques to determine the various contributions to glass-forming ability. Low-temperature time-temperature-transformation diagrams of alloys whose compositions lie at equally spaced points along the tie line from Zr38.5Ti16.5Cu15.25Ni9.75Be20 to Zr46.25Ti8.25Cu7.5Ni10Be27.5 are measured during isothermal annealing of initially amorphous specimens. Surprisingly, for all investigated alloys, a primary quasicrystalline phase forms at a rate which varies substantially with alloy composition. Subsequent constant heating measurements, x-ray-diffraction patterns obtained after various states of annealing, beam bending viscosity results, and previous thermal analysis are all used to describe the influences on crystallization in this series. The description of both the kinetic and thermodynamic aspects of crystallization allows for an explanation of the crystallization mechanism. In addition, it explains why, in this series, thermal stability is greatest in those alloys with the poorest glass-forming ability. Overall, the investigations reveal that simple criteria like thermal stability or high viscosity fail to predict the glass-forming ability in complex bulk glass-forming systems.
|Additional Information:||©2003 The American Physical Society Received 7 June 2002; published 15 May 2003 The authors acknolwedge the support of the National Aeronautics and Space Administration (Grant No. NAG8-1744) and the Department of Energy (Grant No. DEFG-03-86ER45242).|
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|Deposited On:||17 Aug 2007|
|Last Modified:||26 Dec 2012 09:39|
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