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Error in reading diffusivity from database

Posted: Thu Apr 05, 2018 12:59 am
by kamalnath
Hi Brend,

I am relatively new to MICRESS, so I might be doing some silly mistake. I am having a trouble reading diffusivity value from database. I am trying to simulate directional solidfication of Ni-5Nb (wt%)

When running the driving file, I getting the following error message.( The image is from the log file)
Error_Msg.PNG
Snapsnot of the log file
Error_Msg.PNG (82.42 KiB) Viewed 749 times
But, If I use diff command and give user-defined values, the driving file is working fine.

I created the database file using "make_ges5.tcm" (attached) and used the driving file "NbNi_in.txt" (attached)

I wonder whether it is because my MICRESS version is very old ( v5.4 ) or problem in input file. Kindly have a look when you get time.

Regards,
Kamal

Re: Error in reading diffusivity from database

Posted: Thu Apr 05, 2018 9:56 am
by deepumaj1
Hi Kamal,
No problem, everyone starts with silly mistakes. The way you create GES file and everything looks fine. When I ran your driving file with the new micress version, it started fine, though the thermodynamics didn't go well, and I had trying hard errors. But, I'm not getting the same error as yours (invalid diffusion coefficient). So, I think this error might be because you use a very old version of micress, which may not be compatible with the new thermocalc version and the TQ interface. Maybe Bernd can confirm on this. If this is the case, then I would suggest you to use manual diffusion coefficient for time being and see if you are able to simulate your problem. And once you have a stable simulation with manual thermodynamic and diffusion data, you can think of the TQ coupling, which can increase the accuracy of your simulation. At this stage, you may need a new micress version.. 8-)

Best Regards,
Deepu

Re: Error in reading diffusivity from database

Posted: Thu Apr 05, 2018 10:12 am
by ralph
Welcome, Kamal!

next quesion ...
Which Thermo-Calc version did you use to create the GES5 file?

MICRESS 5.4 use a Thermo-Calc library from TC version R (32 bit) and requires an appropriate GES5 file format. For sure, a file generated with a 32 bit version of Thermo-Calc. But there were other internal format change, esp. regarding diffusion data, which broke backwards compatibility of GES5 files.

Ralph

Re: Error in reading diffusivity from database

Posted: Thu Apr 05, 2018 2:50 pm
by kamalnath
Dear Ralph and Deepu,
Thank you very much for your quick responses. I greatly appreciate that.

Deepu: Probably you are right. I am also planning to use manual diffusivity instead of getting diffusivity from the database. Interestingly the reading the information from the thermodynamic database (TCNI8) seems to have no problem. Only when reading mobility database (MOBNI4), I have this issue.

Ralph: Since, I want to use the recent databases TCNI8 and MOBNI4, I am using the thermocalc version R2017b(32bit). As you have suggested, mobility database may have lost compatibility but the thermodynamic database works fine. So, I think I will use user-defined values for now.

Regards,
Kamal

Re: Error in reading diffusivity from database

Posted: Thu Apr 05, 2018 5:12 pm
by Bernd
Hi Kamal,

I am pretty sure that the problem is the combination of a .ges5 file created with a recent version of Thermo-Calc and the old TQ library of MICRESS version 5.4. However, I believe the problem could be only the mobility data, and if you are lucky, perhaps only those for the liquid phase.

In this case you can simply use the following diffusion data which you would have got with a newer MICRESS version at T=1694.98K for manual setting:

Diffusion coefficients in LIQUID (global):
Time: 0.0000 s
Temperature: 1694.98000000000 K
Composition NB: 5.0000E+00 wt%
Components Diff. Coeff. Frequency Term Activation energy
Flux Gradient [cm**2/s] [cm**2/s] [J/mol]
NB NB +5.183E-05 +1.608E-04 +1.596E+04


Diffusion coefficients in FCC_A1 (global):
Time: 0.0000 s
Temperature: 1683.46000000000 K
Composition NB: 3.2224E+00 wt%
Components Diff. Coeff. Frequency Term Activation energy
Flux Gradient [cm**2/s] [cm**2/s] [J/mol]
NB NB +1.090E-08 +0.879 +2.548E+05



Bernd

Re: Error in reading diffusivity from database

Posted: Fri Apr 06, 2018 5:29 pm
by kamalnath
Thank you very much, Brend.

I plan to use these data. But in the manual entry, I need only "Diff.Coeff" and "Activation energy" . What is meant by "Frequency term". I tried looking it up in the manual(v6.3) but could not find it.

For example, for the LIQUID phase:
I understand the numbers 5.183E-05 and 1.596E+04 but what does 1.608E-04 mean ?

-Kamal

Re: Error in reading diffusivity from database

Posted: Sun Apr 08, 2018 6:14 pm
by Bernd
Hi Kamal,

When you input diffusion data manually by using "diagonal d" or the old-style "diff", you are requested for the frequency term and the activation energy (Arrhenius description).
Alternatively, you can also specify the diffusion coefficient and input zero for the activation energy. In the latter case you will have no temperature dependency, of course.

Bernd