This is not a problem in MatCalc, since the handling of size classes during continued nucleation is carried out by MatCalc automatically. With an increase rate of 3% per iteration for the nucleation rate, nucleation still continues when all size classes are filled. If you compare the number density after 20 steps from before and now, you can see that, without the convergence factor setting, more than 100 times more nuclei are formed. A default factor of 2 has resulted in a much faster nucleation, however, also much fewer nuclei.įrom the output above, we can see that less nuclei are created untl the limit of size classes is reached. By choking the nucleation speed, MatCalc has enough time to fill all the created size classes with nuclei. A value of 1.5 would mean that the number can increase by 50%, hence 1.03 stands for an increase of 3% per iteration. A factor of 2 means, that within each time step, the number of new nuclei can double compared to the previous step. The corresponding convergence control parameter is called 'nucleation density increase factor' and it has a default value of 2. Enter into console (there is no GUI implementation for this option as of now): The convergence parameter we are about to change regulates how many nuclei are allowed to form within each time step of the numerical integration procedure. We need to slow down the nucleation, and this can be done by utilizing the MatCalc 'convergence' parameters. Thus, only increasing the 'maximum number of size classes' setting does not change anything in the present case. The pasted lines above read as follows: Cementite_p0 has 12 filled size classes after 20 steps + the number of cementite nuclei is still increasing The '+' sign indicates that nucleation events occur in the particular iteration, 'g' indicates that at least one size class has grown its particles '4e+008' is the number density of precipitates 'd' stands for nucleation site of dislocation. Set the 'update every' frequency in the 'set-simulation-parameter' command menu to 10 and have a close look at the output window: As a result, only 69! size classes from 1000 are filled up with precipitates before the C-supersaturation is so much reduced that nucleation seizes. If you perform the calculation with the same settings as before, the information in the output window indicates that the nucleation process advances to fast to occupy all available size classes in the simulation. Open the 'Phase status' dialog and change the number of size classes in the precipitation tab to #1000. In order to smoothen the precipitate distribution curve, more size classes have to be added.
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