MICRESS Forum

Hello,
I'm trying to model air bubble formation during solidification of Pb-Sn solder alloys. but since MICRESS uses Thermo-Calc database I don't know how to include air bubble in my model. I mean there is no any gas phase in thermo-calc database. do you have any suggestion how to do this simulation? Is that possible at allto do such simulation using micress?

Thanks,

Ghavam

Hi Ghavam,

Of course, it would be best if you could find a database which includes a gas phase. Which one do you have? Do you need more than Pb and Sn? As I understand, you want to have the air bubbles form from or dissolve into the solder. This means that the database should also be able to describe dissolution of O and/or N into the liquid phase. Unfortunately, the solder databases from Thermo-Calc do not include these elements (as far as I have seen).

Perhaps you could try the SGTE databases (SSUB, SSOL) which contain nearly all elements but only on a simple binary level. They also contain Gas phase. Do you have access to these databases?

Otherwise, it would be necessary to either use linearized phase diagrams in MICRESS, or - if you are acquainted to Calphad modelling or know someone who is - insert a simple gas phase into the database you are using...

Bernd

Thanks Bernd,
I made the GES file using both SSUB and SSOL databases and tried to run a simulation but I received an error which says:

# Number of components in database is not
# identical to given number

I have never seen such an error in my previous simulations. do you know what is the problem. I have 3 components in database and defined 3 components in micress, so I can find out what is wrong. Please see the attached files.

Thanks in advance!

Dear Ghavam,

From your attachments alone it is not possible to see the reason of the problem. How many elements did you define in MICRESS? Obviously, 3 elements are found in the .GES5 file, but this seemingly does not match to the number of elements defined in MICRESS...

How did you create the .GES5-file? Can you show the Macro-File (.TCM)? Does the problem occur for both databases (SSOL, SSUB)?

It seems you are working still with a quite old version of MICRESS (by the way, Version 7.1 has been released this week ). There may be compatibility issues in case you use one of the most recent Thermo-Calc versions for creating the .GES5 file.

Bernd

Thanks Bernd,
I don't think thermo-calc version and compatibility are the problems (I use thermo-Calc 2020b) because i extracted GES file for solder alloy itself with the same version and easily ran my simulations. I use the following scripts to get GES file.
go dat
sw
SSUB3
d-e Pb Sn Ar
rej phases *
rest phases Gas Pb_S PB_L SN_S SN_L
get-data
app
SSUB3
d-e Pb Sn Ar
rej phases *
rest phases Gas Pb_S PB_L SN_S SN_L
get data
go gibbs
save
exit
I attached both GES file and drive file.


I want to simulate the effect of gravity on void formation during soldering and for that I'm going to couple my model with FLOW module. For that should I have air bubble (Ar elements in this case) in the liquid phase from the first? or MICRESS will consider it and create gas phase it self?

Is MICRESS able to simulate that at all?

Thank you very much

these are the attached files .

I just get the GES file in binary system using SSUB3 database (only have Pb and N ) and it works perfectly. but the problem is that I want the gas phase in the solder alloy (Pb-Sn). Any idea how to solve the problem? in fact I want N2 gas bubble in the liquid phase and see how they entrapped during solidification in different level of gravity and see the effect of buoyancy force.

Hi Ghavam,

in first place, I don't understand why you attach the same data twice in your script (for creating the .ges5 file). However, your error message above comes because you defined only 1 dissolved component in the input file (concentration data), but the .GES5 file contains 2...

If your goal is to simulate multiphase flow (i.e. a gas bubble floating with the melt), MICRESS unfortunately won't be able to do it in the current version.

Bernd

Thank you very much,
Just the final question. From your explanation I understand that MICRESS is no able to simulate floating one phase (solid or gas) in liquid phase. Is that correct?
And I'm not able to simulate the effect of gravity on buoyancy force and void formation during solidification (soldering in particular) using MICRESS. Is it right?

Thanks again

Dear Ghavam,

Your first statement is correct.

I am not sure whether I understand the second. MICRESS is able to simulate convection which is due to buoyancy forces as consequence of gravity and inhomogeneous liquid density. And MICRESS is able to simulate nucleation and growth of gas bubbles. However, at present we cannot take into account the local hydrostatic pressure when calculating the driving force for nucleation. If this is what you mean, then you are right.

Bernd