Usualy kinetic data obtaned in DSC (or other method) data are used to predict total process rate or degree of transformation. But are there any atempts to separate nucleation and growth rates in heterogeneous process?
The final issue is to predict size distribution of particles in matrix after various heat treatments.
Dear Nikolay Babitskiy, you didn't mentionned thé Matrix (organic, inorganic). Both DSC and DTA are used for nucleation kinetics and quantification. Please check the following documents. My Regards
https://www.researchgate.net/publication/264339377_Effect_of_Simultaneous_Nucleation_and_Crystal_Growth_on_DSC_Crystallization_Peaks_of_Glasses
https://www.researchgate.net/publication/284047716_DTADSC_methods_for_estimation_of_crystal_nucleation_rates_on_glass-forming_melts
Interesting question with great insights. Looking forward to the discussion!
Dear Abdelkader BOUAZIZ, thank you for answer!
It is very useful information.
Now I'm working on kinetic of precipitation in supercooled Al solid solution. But i belive that DSC and modeling approaches maigt be universal. h
~Nikolay
Depending on what your precipitates are, you may be able to use a less commonly known method called thermomagnetometry. If you have access to a TGA or STA machines, you may be able to buy a magnetic attachment which will allow you to conduct the measurement. The change in magnetic susceptibility can then be measured as a function of temperature or for a given isothermal step and there is a direct relationship between precipitate volume fraction, size vs change in susceptibility.
Hi;
The Nucleation rate is determined by the equation: I = dNv/dt
Nv is the number of nucleated crystals.
To determine the nucleation rate, there are two methods:
1- Nv as a function of nucleation time, t, determined with different microscopy methods;
2- Crystallized volume fraction (DTA, DSC, or X-rays) and crystal growth rate with an analysis in the theory of Johnson-Mehl-Avrami-Kolmogorov (JMAK) for an indirect calculation of the nucleation rate.
With my best regards
A possible route could be measuring ‘induction times’. You should do this at fixed T. Meaning you position your DSC in a T-window where you observe metastability. You wait till you start to pick up signal. The onset point (time) where the process starts you label as induction time.
The average induction time at a certain T is according to classical nucleatiom theory (see book Kaschev) is inversely proportional to the nucleation rate.
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