Busch, R. and Kim, Y. J. and Johnson, W. L. (1995) Thermodynamics and kinetics of the undercooled liquid and the glass transition of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy. Journal of Applied Physics, 77 (8). pp. 4039-4043. ISSN 0021-8979 http://resolver.caltech.edu/CaltechAUTHORS:BUSjap95
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Differential scanning calorimetry (DSC) was used to determine the thermodynamic functions of the undercooled liquid and the amorphous phase with respect to the crystalline state of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5bulk metallic glass forming alloy. The specific heat capacities of this alloy in the undercooled liquid, the amorphous state and the crystal were determined. The differences in enthalpy, ∆H, entropy, ∆S, and Gibbs free energy, ∆G, between crystal and the undercooled liquid were calculated using the measured specific heat capacity data as well as the heat of fusion. The results indicate that the Gibbs free energy difference between metastable undercooled liquid and crystalline solid, ∆G, stays small compared to conventional metallic glass forming alloys even for large undercoolings. Furthermore, the Kauzmann temperature, TK, where the entropy of the undercooled liquid equals to that of the crystal, was determined to be 560 K. The Kauzmann temperature is compared with the experimentally observed rate-dependent glass transition temperature, Tg. Both onset and end temperatures of the glass transition depend linearly on the logarithm of the heating rate based on the DSC experiments. Those characteristic temperatures for the kinetically observed glass transition become equal close to the Kauzmann temperature in this alloy, which suggests an underlying thermodynamic glass transition as a lower bound for the kinetically observed freezing process.
|Additional Information:||©1995 American Institute of Physics. Received 29 August 1994; accepted 20 December 1994. The authors would like to thank D. Isheim and S. Friedrichs for their assistance on the DSC experiments and U. Geyer, S. Schneider, E. Bakke, and H. Fecht for valuable help and fruitful discussions. This work was supported by the German Alexander von Humboldt Foundation via the Feodor Lynen Program, the Department of Energy (Grant No. DEFG-03-86ER45242) and the National Aeronautics and Space Administration (Grant No. NAG8-954).|
|Subject Keywords:||ZIRCONIUM BASE ALLOYS; TITANIUM ALLOYS; COPPER ALLOYS; NICKEL ALLOYS; BERYLLIUM ALLOYS; METALLIC GLASSES; LIQUIDS; AMORPHOUS STATE; THERMODYNAMIC PROPERTIES; PHASE TRANSFORMATIONS; SPECIFIC HEAT; SUPERCOOLED LIQUIDS; DSC|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||22 Jun 2006|
|Last Modified:||26 Dec 2012 08:55|
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