Johnson-Mehl-Avrami Equation

[darkelf]

Hello,

Could anyone help shed more light on the Johnson Mehl Avrami equation and how it relates to recrystallization or crystallization? I can't seem to find much on it.

Any information would be appreciated.

Thank you

 

[Mapes]

Do you have a specific question? The first link on Google (a Carnegie Mellon lecture) gives the equation, the characteristics, the applications, and the literature references.

 

[oswaler]

for your question. The Johnson-Mehl-Avrami equation, also known as the Johnson-Avrami-Mehl equation, is a mathematical model used to describe the kinetics of phase transformations, including recrystallization and crystallization. It was first proposed in 1939 by W. A. Johnson and R. Mehl, and later refined by N. Avrami in 1940.

The equation is based on the assumption that the transformation occurs through the nucleation and growth of new phases, and it takes into account the effects of both nucleation and growth rates on the overall transformation kinetics. It is commonly expressed as:

X = 1 - exp[-(kt)^n]

Where X is the fraction transformed, k is the rate constant, t is time, and n is the Avrami exponent. The value of n can vary depending on the specific transformation, but typically ranges from 2 to 4.

The Johnson-Mehl-Avrami equation has been widely used in various fields of science and engineering, including metallurgy, materials science, and geology. It has been shown to accurately describe the kinetics of phase transformations in a variety of materials, making it a valuable tool for understanding and predicting these processes.

I hope this helps to shed some light on the Johnson-Mehl-Avrami equation and its relevance to recrystallization and crystallization. Please let me know if you have any further questions or if I can provide any additional information.