Fecht, H. J. and Perepezko, J. H. and Lee, M. C. and Johnson, W. L. (1990) Thermodynamic properties and crystallization kinetics of glass-forming undercooled liquid Au-Pb-Sb alloys. Journal of Applied Physics, 68 (9). pp. 4494-4502. ISSN 0021-8979 http://resolver.caltech.edu/CaltechAUTHORS:FECjap90
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The heat capacities of liquid and crystalline Au-Pb-Sb alloys in the glass-forming composition range were measured with droplet emulsion and bulk samples. Based on the measured Cp data, the entropy, enthalpy, and Gibbs free-energy differences between the eutectic solid mixture and undercooled liquid were determined as a function of temperature over ~60% of the undercooling range below the liquidus temperature and compared with theoretical predictions. The results indicate an isentropic temperature at 313 (±5) K, which agrees well with experimental data for the glass transition. The thermodynamic evaluation was applied further to develop a kinetics analysis of the nucleation undercooling response during cooling. Use of different approximations for the Gibbs free energy leads to a variation of the prefactor terms of six orders of magnitude for classical nucleation theory and, consequently, large variation in calculated transformation diagrams which is more pronounced with increasing undercooling. Extrapolations into the glass-forming temperature range and the effects of viscosity, transient nucleation, and estimated Kauzmann temperatures on the crystallization kinetics at high undercooling have been evaluated. This analysis reveals the importance of using measured values of thermophysical properties, even if they represent a limited temperature range at modest undercooling, rather than model approximations in order to obtain reliable evaluations of crystallization kinetics at high undercooling in the glass-forming temperature range.
|Additional Information:||Copyright © 1990 American Institute of Physics. Received 27 April 1990; accepted 19 June 1990. Fruitful discussions with Professor D. Turnbull, Professor P. Haasen, and Dr. K Ohsaka and the financial support from NASA (NAS 496954MG3203550, NAG-8-771) and ARO (DAAL 03-90-G-0042) are gratefully acknowledged.|
|Subject Keywords:||GOLD ALLOYS; LEAD ALLOYS; ANTIMONY ALLOYS; LIQUIDS; CRYSTALS; GLASS TRANSFORMATIONS; SPECIFIC HEAT; THERMODYNAMIC PROPERTIES; TEMPERATURE DEPENDENCE; CRYSTALLIZATION; KINETICS; FREE ENTHALPY; SUBCOOLING|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||11 Aug 2006|
|Last Modified:||26 Dec 2012 08:58|
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