MICRESS program

technical aspects of .dri file generation (e.g. debug mode ) etc...
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shaojielv
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MICRESS program

Post by shaojielv » Sun May 16, 2021 8:15 am

Hello, my dear friend,
I'm sorry to bother you in your busy schedule. I would like to ask you some questions about MICRESS, and I hope to get your reply.

First of all, I want to simulate grain precipitation through MICRESS, but I don't know much about the program, so I hope to get your advice.

Secondly, I want to coupling the grain growth and precipitation process in MICRESS, so I don't know whether it can be completed through MICRESS.

Finally, the coupling of simulated dendritic growth and polycrystalline grain growth is discussed.I hope you will give me your advice.


In addition, there are still some unsolved problems in my last question. If possible, I hope you can give some answers.I would be most grateful.https://board.micress.de/viewtopic.php?f=9&t=716

As for the three problems mentioned above, a large part of the reason may be that I do not understand the concept, but I am suffering from not finding other ways to solve these problems, so I hope to get your help, I will be very grateful.Finally, I would like to express my gratitude to you again.
Lv Shaojie

Bernd
Posts: 1504
Joined: Mon Jun 23, 2008 9:29 pm

Re: MICRESS program

Post by Bernd » Sun May 16, 2021 12:01 pm

Dear Lv Shaojie,

Your questions are quite general and need some concretisation. Depending on the real process you consider, there are many aspects of combining grain growth and precipitation:

Typically, the first grain structures which appear during material processing are those coming from the solidification step. If the dendrites e.g. grow in equiaxed morphology (as opposed to directional or columnar growth), the first grain boundaries (i.e. interfaces between grains of the same primary phase) are formed at the regions where the dendrites grow together. In such a solidification grain structure, often there are precipitates of secondary phases, which have formed from the liquid and which are often located at the grain boundaries. These precipitates can be large, because they grew from the liquid phase. A good starting point for such a simulation scenario could be our MICRESS application example A002_AlCu_Temp1d_dri, where precipitates are of theta phase.

After solution heat treatment and/or deformation processes of the cast material including recrystallisation, the grain boundaries may have been completely detached from their original positions, and grain growth is mainly driven by curvature and triple point forces. Under these conditions, the chemical nature of the material often can be ignored, and simulations of grain growth can be performed using only the phase-field solver without concentration coupling. Instead, effects of the grain boundary including misorientation are dominant for the microstructure development (see e.g. A005_Grain_Growth_Misorientation_3D_dri). Pinning effects of small precipitates of other phases can be taken into account indirectly by using a simple particle pinning model (see T022_Grain_Growth_Pinning_Pres_dri), chemical impurities by a drag model (e.g. T023_Grain_Growth_Solute_Drag_dri).

In principle, there is no problem combining the two approaches, i.e. simulating grain growth processes while coupling to concentration fields and including phase transformations/precipitiation. However, such solid state phase transformations typically require very fine grid resolution, which is difficult to combine with large grain sizes: This requires too many grid cells in the simulation setup, and hence extremely high simulation times...

Bernd

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