Interpretation of output - intf.mcr

Exchange about the physics background, diffuse interface theory, etc..
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Sudhee
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Interpretation of output - intf.mcr

Post by Sudhee » Fri Nov 16, 2018 1:21 pm

Dear Bernd,
I have a question about how to "intf.mcr - gives output regarding the interface region". How is this interface tracking parameter calculated (back ground)? I believe that it is calculated from the phase field parameter (please correct me if I am wrong). Is it possible to track the phase field parameter itself?
Thank you.

Best regards,
Sudhee.

Bernd
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Re: Interpretation of output - intf.mcr

Post by Bernd » Mon Nov 19, 2018 12:27 am

Dear Sudhee,

the .intf can be used to visualize the location of interface regions and to distinguish between dual interfaces, triple point regions and higher order interface regions. It displays only integer numbers: 0: no interface, 1: dual interface, 3: triple junction, 6: quadruple region, 10: quintuple, etc.

Unfortunately, it is not easily possible to create an output for the phase-field parameter. To have the full information, it would be necessary to create an extra output for each grain, which can be numerous. If grains of different phases are considered, the .frac* outputs correspond to the phase-field parameter of those grains.

Bernd

Sudhee
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Re: Interpretation of output - intf.mcr

Post by Sudhee » Thu Nov 22, 2018 10:33 am

Dear Brend,
Thank you for the answer. Yes, I understand that it is a very tedious task to get the phase field parameter as output. But, .intf* output helps to identify the exact interface points.
I have one more question about the interpretation. If you look at the figure attached and follow the green line (after 300s isothermal holding at 500 C), I see that there is depletion of Mn in the ferrite region near the interface. Inside the interface, there is a sudden rise in concentration near the ferrite region and then a drop to the nominal value. In the austenite region, there is no enrichment.
My question is if the mass balance, corresponding to depletion of Mn in ferrite, is happening inside the interface? If so, when I am interpreting the results can I say the same as we cannot see the enrichment in austenite? Could you please help me with this.
Thank you in advance.

Sudhee.
Attachments
Concentration profile of Mn.png
Concentration profile of Mn.png (54.55 KiB) Viewed 1084 times

Bernd
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Re: Interpretation of output - intf.mcr

Post by Bernd » Thu Nov 22, 2018 4:49 pm

Hi Sudhee,

If you equilibrate two phases with initially identical concentration, there will always be a "demixing" of composition with enrichment in the phase with higher solubility for the corresponding element, and depletion in the other. The shape and widths of the two peaks will depend on one hand on the diffusivities in both phases, and on the other hand on the movement of the interface.

In your case, one of the peaks is mainly outside the interface region, and the other one is fully inside. With this information I would assume the interface is moving to the right, leading to the asymmetric shapes and the shift with respect to the interface location. You should be able to see that, if you would add the initial interface position in your plot.

In any case, you definitively have an enrichment of Mn in austenite, even if it is inside the interface. An alternative way to proof that would be to use the phase concentration outputs for each phase (*.c?pha1 and *.c?pha2) for plotting, which are defined everywhere where the corresponding phase is present (i.e. also inside the interface).

I hope this explanation is helpful.

Bernd

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