Extension of the classical theory of crystallization to non-isothermal regimes: Application to nanocrystallization processes

JOURNAL OF ALLOYS AND COMPOUNDS

卷:544

Article

Blazquez, J. S.¹  Borrego, J. M.¹  Conde, C. F.¹  Conde, A.¹  Lozano-Perez, S.² 

[1] Univ Seville, CSIC, Inst Ciencia Mat, Dept Fis Materia Condensada, E-41080 Seville, Spain

[2] Univ Oxford, Dept Mat, Oxford OX1 3PH, England

关键词: Johnson-Mehl-Avrami-Kolmogorov equation;    Crystallization;    Phase transformation kinetics;    Nanocrystalline microstructure;   

DOI  :  10.1016/j.jallcom.2012.08.002

来源: Elsevier

【 摘 要 】

The non-isothermal kinetics of primary crystallization processes is studied from numerically generated curves and their predictions have been tested in several nanocrystallization processes. Single processes and transformations involving two overlapped processes in a non-isothermal regime have been generated and deviations from isokinetic behavior are found when the overlapped processes have different activation energies. In the case of overlapped processes competing for the same type of atoms, the heating rate dependence of the obtained Avrami exponent can supply information on the activation energies of each individual processes. The application to experimental data of nanocrystallization processes is consistent with a limited growth approximation. In the case of preexisting crystallites in the as-cast samples, predictions on the heating rate dependence of the obtained Avrami exponents of multiple processes have been confirmed. (C) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

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