The lower and upper limit of the Avrami index (n) and the related physical meaning for the lower or upper Avrami index (n) in terms of nucleation.
Between 1 and 4. See: B. Wunderlich. Macromolecular Physics. Acad. Press. New York. 1976. Vol. 2.
The Avrami equation describes how solids transform from one phase to another at constant temperature. The equation was first derived by Kolmogorov in 1937 and popularized by Melvin Avrami in a series of papers published in the Journal of Chemical Physics from 1939 to 1941. The Avrami index, n, was held to have an integer value between 1 and 4: this is related to nucleation (homogeneus +1, heterogeneous +0) and growth rate (linear +1, superficial +2, 3D +3). If the nuclei are preformed, and so all present from the beginning, the transformation is only due to the 3-dimensional growth of the nuclei and n has a value of 3 (3=0+3).
refs
Avrami, M (1939). "Kinetics of Phase Change. I. General Theory". Journal of Chemical Physics 7 (12): 1103–1112. Bibcode:1939JChPh...7.1103A. doi:10.1063/1.1750380.
Avrami, M (1940). "Kinetics of Phase Change. II. Transformation-Time Relations for Random Distribution of Nuclei". Journal of Chemical Physics 8 (2): 212–224. Bibcode:1940JChPh...8..212A. doi:10.1063/1.1750631.
Avrami, M (1941). "Kinetics of Phase Change. III. Granulation, Phase Change, and Microstructure". Journal of Chemical Physics 9 (2): 177–184. Bibcode:1941JChPh...9..177A. doi:10.1063/1.1750872.
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