instruction

solid-solid phase transformations, influence of stresses and strains
Jane
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instruction

Post by Jane » Sun May 01, 2022 7:47 am

Dear everyone,

I don't understand the specific meaning of the "front" instruction in nucleation. I understand it according to the manual, but when I use this instruction in gamma-alpha, I find that nucleation does not occur, so I think I should I don't know the instruction yet, or can the instruction be applied in solid-state phase transition? Or does it need to be used in a specific situation?
In addition, what I want to ask is the dislocation in "# Type of coupling?". If I don't study recrystallization, I just want to couple concentration and dislocation. Does such coupling make sense? Or what will happen when they are coupled?

Jane

Bernd
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Re: instruction

Post by Bernd » Mon May 02, 2022 5:45 pm

Dear Jane,

"front" nucleation means selecting locations for nucleation of new seeds which shall appear in "front" of an interface with a certain distance to a given phase. The corresponding interface is selected by a reference phase (the phase in which nucleation will take place) and a substrate phase (the phase at a certain distance to which nucleation shall happen). If you e.g. want to place nuclei of a certain precipitate phase into the melt at a certain distance from a growing fcc-dendrite, you would select the melt phase as reference phase and the fcc phase as substrate phase, and specify a suitable distance in µm.

"dislocation" coupling is used only in a relatively specific setting where you want to read in the spatial distribution of the dislocation density from a file. Unfortunately, this only works well in case of a single-phase grain microstructure, and the purpose is to simulate recrystallisation. Alternatively, a dislocation density can be defined without "dislocation" coupling, if recrystallisation is switched on for a phase, and the "dislocation density" option is chosen instead of "stored energy" for defining the recrystallisation energy.
Apart from recrystallisation, the dislocation density by now is used further for defining a solute diffusivity which is enhanced by pipe-diffusion.

Bernd

Jane
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Re: instruction

Post by Jane » Tue May 03, 2022 3:31 am

Dear Bernd,

Thank you so much for taking the time to reply to me.
1. You are using melt here, does that mean that front can only be used in solidification? Can't it be used in solid state phase transition? Or it doesn't work in solid-state phase transitions.
2. Another question is that the final structure in the previous file is two phases (such as austenite and ferrite), so can I see the two phases in the initial structure after I restart the file as the same phase? Or is this initial organization the same as the final output in the last driver file?
3.Why did I get this error at the end of the run? i didn't understand.

# Reading restart file: FeCMn.rest
# Restart file version number: 30
# Concentration field read
# Grain number field read

Unable to read from file FeCMn.rest
STOP in routine initRestart
while reading grain data, iosError: 5



Looking forward to your reply, thank you very much.

Jane

Jane
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Re: instruction

Post by Jane » Tue May 03, 2022 2:39 pm

Replenish,
And it is mentioned in the manual that the relevant parameters can only be changed by using structure_only, but why is there no structure_only in mine, but with_flow?
If you have time, I would like to help answer related questions, thank you very much.

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

Re: instruction

Post by Bernd » Tue May 03, 2022 4:10 pm

Dear Jane,

Regarding your follow-up questions about "front" nucleation: This nucleation type is not specific for any type of phases, and thus of course can also be used in case of solid-solid transformations.

Regarding your question about the error on reading the .rest file: It is difficult to explain the error without exact knowledge of what you have been doing. However, it is quite reasonable that you changed parameters which are not allowed to change (because they change the data structure itself and make it impossible to go on reading correctly). The old sub-option "structure_only", which allows a much wider range of parameters to be changed upon restart, is not existing anymore since version 7.0. It has been shifted into section "Structure from restart file", because its character is more the definition of an initial microstructure than a restart. However, the functionality has remained unchanged.

Bernd

Jane
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Re: instruction

Post by Jane » Tue May 03, 2022 4:26 pm

Dear Bernd,

Thank you very much for taking the time to reply to my message.
You say "front" is not specific to any type of phase, I'm perfectly fine with that, but if I select "front" in the phase transition from austenite to ferrite and nothing happens, can you explain How does the front function in the austenite-ferrite transformation?
I'll attach my driver files, hope you can help me check the reason for this error.
best wishes.

Jane
Attachments
FeCMn _restart.dri
(32.33 KiB) Downloaded 96 times

Bernd
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Re: instruction

Post by Bernd » Tue May 03, 2022 4:45 pm

Dear Jane,

I am confused, because you seemingly do not use the "front" keyword in your input file...

Bernd

Jane
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Re: instruction

Post by Jane » Tue May 03, 2022 5:37 pm

Dear Bernd,

I'm sorry I didn't make it clear, I asked two questions here.
The first one is about the application of "front".
The second question is: Regarding the problem of reading the initial organization file from the file, because the 7.0 and above versions do not have "structrure_only" in the restart, so I started to read the initial organization, as shown on the right, I am I want to read the file, but the reading is over, and when the simulation reaches 16S, the organization is as shown on the left. I really don't understand why.The following is my driver file, I believe you will have a lot of experience, thank you very much.
best wishes.

Jane
Attachments
FeCMn _restart.dri
(29.41 KiB) Downloaded 83 times
restart.png
restart.png (67.79 KiB) Viewed 1760 times

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

Re: instruction

Post by Bernd » Tue May 03, 2022 6:11 pm

Dear Jane,

I don't understand why you did not read the initial microstructure from the .rest file in the way I proposed (in section "Structure from restart file").
Instead, you have read the initial structure from the .phas input (as .vtk), but erroneously set both phases to phase number 1:

# Phase numbers taken out of the VTK table needs to be redefined
# (N.B. phases are sorted by order of appearance)
# VTK phase number 1 corresponds to MICRESS phase?
1
# VTK phase number 2 corresponds to MICRESS phase?
# 2
1



This means, you start from a single phase structure, and the few lateral grains of phase 2 probably have formed by nucleation...

Bernd

Jane
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Re: instruction

Post by Jane » Wed May 04, 2022 12:18 pm

Dear Bernd,
According to what you said, I restarted the file, the specific file is as follows, but the following error still occurred.The phase transition cannot proceed.

# Reading restart file #1: FeCMn.rest
# Restart file version number: 30
# Concentration field read
# Grain number field read

Unable to read from file FeCMn.rest
STOP in routine initRestart
while reading grain data, iosError: 5


best wishes
Jane
Attachments
FeCMn _restart.dri
(34.06 KiB) Downloaded 86 times

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