spinodal decomposition

dendritic solidification, eutectics, peritectics,....
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wzb198910
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spinodal decomposition

Post by wzb198910 » Wed Apr 26, 2017 5:30 pm

Hello,
Recently, I am try to simulate the process of spinodal decomposition.
Question 1:
Different from the normal solidification which should nucleation first, the spinodal decomposition have no nucleation.
Therefore I set Grain input and Data for further nucleation as following:
# Grain input
# ===========
# Type of grain positioning?
# Options: deterministic random [deterministic_infile] from_file
deterministic
# NB: the origin of coordinate system is the bottom left-hand corner,
# all points within the simulation domain having positive coordinates.
# Number of grains at the beginning?
0
#
# Data for further nucleation
# ===========================
# Enable further nucleation?
# Options: nucleation nucleation_symm no_nucleation [verbose|no_verbose]
no_nucleation
#
But I got an incorrect result after finished simulation.
I search the forum but there is less information about spinodal, so I want to know whether the process without nucleation like spinodal decomposition can be simulated by MICRESS and whether the Grain input and Data for further nucleation setting is correct?
More Detail please see the attachment: CuNi_in.txt

Question 2:
During the simulation, I coupled the Cu-Ni thermodynamic database.
When I used CuNi.GES5 that generated based the Cu-Ni database which defined by myself according to the reference, but I met the error as following:
# Warning: GES5 file format and TQ library (32/64 bit) may be incompatible!
# Index relations between TC and MICRESS
# --------------------------------------
# The database contains the following components:
# Number of components in database is not
# identical to given number
But I used CuNi.GES5 that generated based on TCFE7, no error appeared.

PS: I simulate the solidification of Cu70Ni30 at% at 500K.
The attachments are CuNi_in.txt is the driving file; Cu_Ni_1.GES5.txt is the GES5 file that generated based on TCFE7.
the Cu-Ni database which defined by myself; Cu_Ni_2.GES5.txt is the GES5 file that generated based on Cu-Ni_2.tdb.
Attachments
Cu_Ni_2.GES5.txt
(6.17 KiB) Downloaded 187 times
Cu-Ni_2.TDB.txt
(2.89 KiB) Downloaded 205 times
Cu_Ni_1.GES5.txt
(12.73 KiB) Downloaded 252 times
CuNi_in.txt
(17.29 KiB) Downloaded 244 times

Bernd
Posts: 1505
Joined: Mon Jun 23, 2008 9:29 pm

Re: spinodal decomposition

Post by Bernd » Thu Apr 27, 2017 11:57 am

Dear wzb198910,

spinodal composition cannot be simulated with MICRESS. The reason for that is the general phase-field concept which separates the process of phase transformation from the diffusion process. There are dedicated phase-field concepts for that, but those are in turn not capable of simulating phase transformations of realistic materials on the µm scale.
The workaround for that problem in MICRESS is to use nucleation for creating the second phase. This is quite realistic as long as temperature and composition are not close to the spinodal point. However, if you really want to simulate critical coalescence (which is always difficult as it spans length-scales) you need other software.

For your second problem, I assume that the .ges5 file has been created either using an incompatible Thermo-Calc version or something went wrong. When I try to create a .ges5 file from your attached .tdb using Thermo-Calc 2016b, I get an error message on the "get" command about missing Reference. Nevertheless, I can read the .ges5 file with MICRESS while I can't read the one you attached...

Bernd

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