Nucleation during continuous cooling—application to massive transformations
1974; University of Toronto Press; Volume: 22; Issue: 7 Linguagem: Inglês
10.1016/0001-6160(74)90054-6
ISSN1878-0768
AutoresS. Bhattacharyya, John H. Perepezko, T. B. Massalski,
Tópico(s)Chemical Thermodynamics and Molecular Structure
ResumoAbstract A model is examined of nucleation during continuous cooling as it applies to the transformation kinetics in composition-invariant massive transformations. The resulting theory suggests that in massive transformations occurring under conditions of low undercooling the relationship between the nucleation temperature and the cooling rate is of a simple parabolic form dT/dt = K(ΔT)2, where K is a constant related to the initial shape of the nucleus, the driving force, and other properties of the material, and ΔT is the degree of undercooling. A close inspection of the available data in a number of alloy systems and in pure iron suggests that in massive transformations occurring during continuous cooling the initial thermal arrest temperature is the temperature at which nucleation first takes place. The good agreement between the proposed theory and experimental data confirms that nucleation is the rate controlling step in massive reactions.
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