input of minimal and maximal rex energy

ripening phenomena, dislocations, grainboundary topology
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zhubq
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Joined: Mon Jun 22, 2009 7:33 pm

input of minimal and maximal rex energy

Post by zhubq » Tue Apr 20, 2010 2:20 am

what is the meaning of this input:
input of minial and maximal rex energy

I think this is only added in latest version of MICRESS

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

Re: input of minimal and maximal rex energy

Post by Bernd » Wed Apr 21, 2010 5:14 pm

Dear zhubq,

This input is requested as part of the nucleation input data if for the nucleated phase the recrystallisation model is activated. It is a feature in the new release which allows simulation of consecutive process steps using MICRESS.
Normally, for recrystallisation, new growing nuclei are supposed to have no dislocations and thus a recrystallisation energy of 0, which was the default in the older MICRESS versions. But if one starts a simulation from the liquid and goes through solidification in order to get a reasonable initial structure for recrystallisation (without explicitely handling deformation), then it is necessary to provide the solid phase with a recrystallisation energy via the nucleation input!

Thus, the new version provides more flexibility for multi-process step simulations. In the case of a "normal" recrystallisation simulation, the minimum and maximum value of the reX energy should be set to 0.

Bernd

nokkikku
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Re: input of minimal and maximal rex energy

Post by nokkikku » Tue Feb 08, 2011 2:39 pm

Hallo Bern,

but what's the difference of the min and max rex energy and the 'critical recrystallisation energy'?

Many thanks and best regards

Bernd
Posts: 1148
Joined: Mon Jun 23, 2008 9:29 pm

Re: input of minimal and maximal rex energy

Post by Bernd » Wed Feb 09, 2011 10:23 am

Hallo nokkikku,

In our recrystallisation model, the stored energy of the deformed grains constitute the driving force the reX process, as well for growth as for nucleation. The "critical recrystallisation energy" is just the minimum value of the stored energy required to allow a new seed of the same phase to be formed in such a deformed grain (at interfaces or triple junctions, the maximum value of the locally present grains is used as criterium).
This is completely independent from the recrystallisation energy which you give the new grains by the above described input, which is anticipating a fictive deformation process in a later process step.

Bernd

nokkikku
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Re: input of minimal and maximal rex energy

Post by nokkikku » Wed Feb 09, 2011 2:45 pm

Hallo Bernd,


Thanks for the quick reply as always. I have just noticed that the min and max energy is possible both in the parent grains and the product grains. So that you mentioned stored energy in solidified structured for the follwing ReX, should be the stored energy in the product grains.


However, I understand that min and max ReX energy in nucleation mode is also useful if we simulate gamma-alpha transformation from deformed austenite, right? This time it is the stored energy in the parent grains.

I remember you explained me once and Markus showed me how to do.

# Which nucleation driving force shall be used?
# Options: undercooling recrystall
undercooling

# Input of minimal and maximal recrystallisation energy:
# (dG contribution only if energy is 0 on one side!)
# Minimum of recrystallisation energy? [J/cm**3]
xxx
# Maximum of recrystallisation energy? [J/cm**3]
xxx

Bernd
Posts: 1148
Joined: Mon Jun 23, 2008 9:29 pm

Re: input of minimal and maximal rex energy

Post by Bernd » Wed Feb 09, 2011 5:25 pm

This is true. Whether you call them parent or product grains depends on the process you are referring to. In the code, there are two places where the minimum and maximum reX energy is requested: In the grain input and in the nucleation input. The reX energy values always refer to the "product" of initial grain setting or nucleation, but may be "parent" for the subseqent process.

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