Hello Bernd,
Thank you for your advice.
I have already tried again after changing some parameters. And the side branches appeared. However, I still have some questions.
1) I reset the interface energy to 5.0E-06 from 1.2E-05 in case of simulating two dendrites growth process. Yes, the side branches appears. But the secondary dendrite arm spacing is too small, less than half of experimental data. In addition, from some papers authors always set interface energy to 3.0E-05 between phase liquid and fcc in case of stainless steel. My materials is similar to theirs, so I do not know the interface energy dropping into 5.0E-06 is suitable or not in order to just occur side branches.
2) The primary dendrite arm spacing, secondary dendrite arm spacing, morphology of dendrite tip and their influencing factors are always discussed. However, I do not know which factors can remarkably affect the thickness of primary dendrite(not including the length of side branches). In my opinion, the problem of my simulation is that the thickness of primary dendrite is too thick and the spacing of two dendrites is limited so the dendrite growth looks like cell growth when running two dendrite growth process and setting distance between two nucleation grains by using experimental primary dendrite arm spacing. Thus, I want to how to solve this.
3) According to .log file, the dG is about -18J/cm3. However, from the .driv file it shows the maximum driving is only -3 or -4.5. I reset some parameters and tried again, however the value did not change too much.
Weld solidification
Re: Weld solidification
Dear superabc,
If the dendrite trunk is so thick that there is no space for side branches, the situation seems to be close to cellular growth (if numerics are not completely wrong)!
Please keep in mind that the liquid diffusivity as well as interface energy strongly influence primary and secondary distances, and that both are essentially unknown (the value of 10-5cm2/s for the diffusivity in liquid in the database is just a dummy!). Thus, the correct procedure would be to estimate one of the two values, and calibrate the other one such as to get the correct secondary distance.
If then, for the given primary distance, the dendrites still look too cellular, you could try to set only one dendrite to the corner, and observe selection of the primary distance.
Please also keep in mind that a comparison of 2D simulation with 3D experiments can be misleading: 2D primary spacings are typically somewhat bigger than 3D spacings.
Comparison of dG from the .log file (=initial driving force at the point which was first checked for nucleation) and the .driv output (actual local driving force at the output time, including curvature effects) does not make sense! If the maximum driving force in the .driv output does not decrease when increasing the interface mobility, it is just made up by curvature, and mobility is already high enough to be diffusion (and curvature) limited.
Best regards
Bernd
If the dendrite trunk is so thick that there is no space for side branches, the situation seems to be close to cellular growth (if numerics are not completely wrong)!
Please keep in mind that the liquid diffusivity as well as interface energy strongly influence primary and secondary distances, and that both are essentially unknown (the value of 10-5cm2/s for the diffusivity in liquid in the database is just a dummy!). Thus, the correct procedure would be to estimate one of the two values, and calibrate the other one such as to get the correct secondary distance.
If then, for the given primary distance, the dendrites still look too cellular, you could try to set only one dendrite to the corner, and observe selection of the primary distance.
Please also keep in mind that a comparison of 2D simulation with 3D experiments can be misleading: 2D primary spacings are typically somewhat bigger than 3D spacings.
Comparison of dG from the .log file (=initial driving force at the point which was first checked for nucleation) and the .driv output (actual local driving force at the output time, including curvature effects) does not make sense! If the maximum driving force in the .driv output does not decrease when increasing the interface mobility, it is just made up by curvature, and mobility is already high enough to be diffusion (and curvature) limited.
Best regards
Bernd
Re: Weld solidification
Hi Bernd:
Right now, I am confused about how to continue a stopped simulation after modifying some parameters, like kinetic coefficient, interface energy and so on. I have already read the "Restart potions" of manual. However, I still do not know how to carry out. Can you explain the detail process? After stopping simulation, I should do what on the driv. file or output file or some other things.
I am looking forward to your replay.
Thanks!
Superabc
Right now, I am confused about how to continue a stopped simulation after modifying some parameters, like kinetic coefficient, interface energy and so on. I have already read the "Restart potions" of manual. However, I still do not know how to carry out. Can you explain the detail process? After stopping simulation, I should do what on the driv. file or output file or some other things.
I am looking forward to your replay.
Thanks!
Superabc
Re: Weld solidification
Hi superabc,
You should proceed in the following way:
1.) Make a copy of the restart file <output_name>.rest. I personally use to make a name modification like <output_name>_r.rest and copy it to the same location as the driving file <output_name>.dri.
2.) Modify the <output_name>.dri:
- In "Restart options" replace "new" by "restart"
- In the next line, put the name (and path if you have put it elsewhere) of the restart file without extension <output_name>_r
- In section "Name of output files", replace "overwrite" with "append" if you want the further output to be appended to the already existing result files. Otherwise, change the name of the output files in order not to overwrite (and lose) them and to get the further output in a separated set of files.
3.) Start the simulation again. If you want to be double sure make a backup copy of the results before rerunning the simulation.
You should proceed in the following way:
1.) Make a copy of the restart file <output_name>.rest. I personally use to make a name modification like <output_name>_r.rest and copy it to the same location as the driving file <output_name>.dri.
2.) Modify the <output_name>.dri:
- In "Restart options" replace "new" by "restart"
- In the next line, put the name (and path if you have put it elsewhere) of the restart file without extension <output_name>_r
- In section "Name of output files", replace "overwrite" with "append" if you want the further output to be appended to the already existing result files. Otherwise, change the name of the output files in order not to overwrite (and lose) them and to get the further output in a separated set of files.
3.) Start the simulation again. If you want to be double sure make a backup copy of the results before rerunning the simulation.
Re: Weld solidification
Hi Bernd,
Thanks for your explanation.
While, I still have two questions:
1) It is about how to set restart file. According to your specification, first I changed "results_rest.mcr" file into "results_restart_rest. mcr"file and put it into another new file where the new output files would be. And parameters of some parts in the driving file had already reset, but when running it showed error. Here, I put the changing parts in the driving file and error part.
Restart driving file
#
# Restart options
# ===============
# Restart using old results?
# Options: new restart [reset_time]
restart
wd_results\wd_results_6_restart
#
# Name of output files
# ====================
# Name of result files?
wd_results\wd_results_6
# Overwrite files with the same name?
# Options: overwrite write_protected append
# [zipped|not_zipped|vtk]
# [unix|windows|non_native]
append
#
Error
# Other numerical parameters
# ==========================
# Phase minimum?
1.00E-4
# Interface thickness (in cells)?
3.00
Error: unable to re-open 'logfile' after 'flushing'!
Press any key to exit
2) Another question is that I wanted to try to run one example for practice. There were two phases during simulation. And input elements were fe, cr, ni, c, si, mn. Liquidus temperature was 1740K. When the temperature was more than 1700K, mobility between δ and γ. And so on, I will show the info. file.
When I tried to run, the error was as follows and sometimes the error was different.
Driving file
# Data for phase interaction 1/ 2:
# ---------------------------------
# Simulation of interaction between phase 1 and 2?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control]
phase_interaction
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1.0
# I.e.: avg +1.00 smooth +45.0 max +2.00000E+01
# Type of surface energy definition between phases 1 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 2? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
7.000000000000E-05
# Type of mobility definition between phases 1 and 2?
# Options: constant temp_dependent dg_dependent
temp_dependent
# File for kinetic coefficient between phase 1 and 2?
C:\GES\Info.txt
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
# Data for phase interaction 2 / 2:
# ---------------------------------
# Simulation of interaction between phase 0 and 1?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control]
phase_interaction
# Type of surface energy definition between phases 2 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 2 and 2? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
4.000000000000E-05
# Type of mobility definition between phases 2 and 2?
# Options: constant temp_dependent dg_dependent
constant
# Kinetic coefficient mu between phases 2 and 2? [cm**4/(Js)]
3.0000000000E-03
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
anisotropic
# Anisotropy of interfacial stiffness? (cubic)
# 1 - delta * cos(4*phi), (delta =delta_stiffness =15*delta_energy)
# Coefficient delta (<1.) ?
0.0130000
# Anisotropy of interfacial mobility? (cubic)
# 1 + delta * cos(4*phi)
# Coefficient delta (<1.) ?
0.0130000
#
# Concentration data
# ==================
# Number of dissolved constituents? (int)
5
# Type of concentration?
# Options: atom_percent (at%)
# weight_percent (wt%)
weight_percent
#
# Options: diff no_diff infinite infinite_restricted
# multi database_global database_local from_file
# [+b] for grain-boundary diffusion
# ('multi' can be followed by a string of "n", "d", "g", "l", or "f"
# to describe each contribution: respectively no diffusion,
# user-defined diffusion coefficient,'global' or 'local' value from
# database, and 'from file, the default is global values from database).
# Extra line option (prefactor on time step): cushion <0-1>
# Extra line option: infinite_limit [cm**2/s]
# How shall diffusion of component 1 in phase 0 be solved?
database_global
# How shall diffusion of component 1 in phase 1 be solved?
database_global
# How shall diffusion of component 1 in phase 2 be solved?
database_global
# How shall diffusion of component 2 in phase 0 be solved?
database_global
# How shall diffusion of component 2 in phase 1 be solved?
database_global
# How shall diffusion of component 2 in phase 2 be solved?
database_global
# How shall diffusion of component 3 in phase 0 be solved?
database_global
# How shall diffusion of component 3 in phase 1 be solved?
database_global
# How shall diffusion of component 3 in phase 2 be solved?
database_global
# How shall diffusion of component 4 in phase 0 be solved?
database_global
# How shall diffusion of component 4 in phase 1 be solved?
database_global
# How shall diffusion of component 4 in phase 2 be solved?
database_global
# How shall diffusion of component 5 in phase 0 be solved?
database_global
# How shall diffusion of component 5 in phase 1 be solved?
database_global
# How shall diffusion of component 5 in phase 2 be solved?
database_global
#
# Interval for updating diffusion coefficients data? [s]
1.00
#
#
# Phase diagram - input data
# ==========================
#
# List of phases and components which are stoichiometric:
# phase and component(s) numbers
# List of concentration limits (wt%):
# <Limits>, phase number and component number
# Switches: <stoich_enhanced_{on|off}> <solubility_{on|off}>
# End with 'no_more_stoichio' or 'no_stoichio'
no_stoichio
Info.
# Temperature Kinetic coefficient
# [K] [cm**4/(Js)]
1700.00 4.00E-04
1600.00 1.00E-04
1500.00 4.00E-05
1400.00 7.00E-06
1300.00 1.00E-06
1200.00 1.00E-07
1100.00 1.00E-08
Error
# Concentration data
# ==================
# Number of dissolved constituents? (int)
#
#
#
#
#
__END__
#
Input error in routine leseEingabe
Input: anisotropic
#
Thanks. I am looking forward to your replay.
Thanks for your explanation.
While, I still have two questions:
1) It is about how to set restart file. According to your specification, first I changed "results_rest.mcr" file into "results_restart_rest. mcr"file and put it into another new file where the new output files would be. And parameters of some parts in the driving file had already reset, but when running it showed error. Here, I put the changing parts in the driving file and error part.
Restart driving file
#
# Restart options
# ===============
# Restart using old results?
# Options: new restart [reset_time]
restart
wd_results\wd_results_6_restart
#
# Name of output files
# ====================
# Name of result files?
wd_results\wd_results_6
# Overwrite files with the same name?
# Options: overwrite write_protected append
# [zipped|not_zipped|vtk]
# [unix|windows|non_native]
append
#
Error
# Other numerical parameters
# ==========================
# Phase minimum?
1.00E-4
# Interface thickness (in cells)?
3.00
Error: unable to re-open 'logfile' after 'flushing'!
Press any key to exit
2) Another question is that I wanted to try to run one example for practice. There were two phases during simulation. And input elements were fe, cr, ni, c, si, mn. Liquidus temperature was 1740K. When the temperature was more than 1700K, mobility between δ and γ. And so on, I will show the info. file.
When I tried to run, the error was as follows and sometimes the error was different.
Driving file
# Data for phase interaction 1/ 2:
# ---------------------------------
# Simulation of interaction between phase 1 and 2?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control]
phase_interaction
# 'DeltaG' options: default
# avg ... [] max ... [J/cm**3] smooth ... [degrees] noise ... [J/cm**3]
avg 1.0
# I.e.: avg +1.00 smooth +45.0 max +2.00000E+01
# Type of surface energy definition between phases 1 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 1 and 2? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
7.000000000000E-05
# Type of mobility definition between phases 1 and 2?
# Options: constant temp_dependent dg_dependent
temp_dependent
# File for kinetic coefficient between phase 1 and 2?
C:\GES\Info.txt
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
isotropic
#
# Data for phase interaction 2 / 2:
# ---------------------------------
# Simulation of interaction between phase 0 and 1?
# Options: phase_interaction no_phase_interaction
# [standard|particle_pinning[_temperature]|solute_drag]
# | [redistribution_control]
phase_interaction
# Type of surface energy definition between phases 2 and 2?
# Options: constant temp_dependent
constant
# Surface energy between phases 2 and 2? [J/cm**2]
# [max. value for num. interface stabilisation [J/cm**2]]
4.000000000000E-05
# Type of mobility definition between phases 2 and 2?
# Options: constant temp_dependent dg_dependent
constant
# Kinetic coefficient mu between phases 2 and 2? [cm**4/(Js)]
3.0000000000E-03
# Shall misorientation be considered?
# Options: misorientation no_misorientation [transition LAB/HAB in degree]
no_misorientation
# Is interaction isotropic?
# Optionen: isotropic anisotropic [harmonic_expansion]
anisotropic
# Anisotropy of interfacial stiffness? (cubic)
# 1 - delta * cos(4*phi), (delta =delta_stiffness =15*delta_energy)
# Coefficient delta (<1.) ?
0.0130000
# Anisotropy of interfacial mobility? (cubic)
# 1 + delta * cos(4*phi)
# Coefficient delta (<1.) ?
0.0130000
#
# Concentration data
# ==================
# Number of dissolved constituents? (int)
5
# Type of concentration?
# Options: atom_percent (at%)
# weight_percent (wt%)
weight_percent
#
# Options: diff no_diff infinite infinite_restricted
# multi database_global database_local from_file
# [+b] for grain-boundary diffusion
# ('multi' can be followed by a string of "n", "d", "g", "l", or "f"
# to describe each contribution: respectively no diffusion,
# user-defined diffusion coefficient,'global' or 'local' value from
# database, and 'from file, the default is global values from database).
# Extra line option (prefactor on time step): cushion <0-1>
# Extra line option: infinite_limit [cm**2/s]
# How shall diffusion of component 1 in phase 0 be solved?
database_global
# How shall diffusion of component 1 in phase 1 be solved?
database_global
# How shall diffusion of component 1 in phase 2 be solved?
database_global
# How shall diffusion of component 2 in phase 0 be solved?
database_global
# How shall diffusion of component 2 in phase 1 be solved?
database_global
# How shall diffusion of component 2 in phase 2 be solved?
database_global
# How shall diffusion of component 3 in phase 0 be solved?
database_global
# How shall diffusion of component 3 in phase 1 be solved?
database_global
# How shall diffusion of component 3 in phase 2 be solved?
database_global
# How shall diffusion of component 4 in phase 0 be solved?
database_global
# How shall diffusion of component 4 in phase 1 be solved?
database_global
# How shall diffusion of component 4 in phase 2 be solved?
database_global
# How shall diffusion of component 5 in phase 0 be solved?
database_global
# How shall diffusion of component 5 in phase 1 be solved?
database_global
# How shall diffusion of component 5 in phase 2 be solved?
database_global
#
# Interval for updating diffusion coefficients data? [s]
1.00
#
#
# Phase diagram - input data
# ==========================
#
# List of phases and components which are stoichiometric:
# phase and component(s) numbers
# List of concentration limits (wt%):
# <Limits>, phase number and component number
# Switches: <stoich_enhanced_{on|off}> <solubility_{on|off}>
# End with 'no_more_stoichio' or 'no_stoichio'
no_stoichio
Info.
# Temperature Kinetic coefficient
# [K] [cm**4/(Js)]
1700.00 4.00E-04
1600.00 1.00E-04
1500.00 4.00E-05
1400.00 7.00E-06
1300.00 1.00E-06
1200.00 1.00E-07
1100.00 1.00E-08
Error
# Concentration data
# ==================
# Number of dissolved constituents? (int)
#
#
#
#
#
__END__
#
Input error in routine leseEingabe
Input: anisotropic
#
Thanks. I am looking forward to your replay.
Re: Weld solidification
Hi superabc,
For your first question, I think the answer is that you can only "append" if all the result files are already there! As I understood, you created a new directory for the results and put "wd_results_6_restart" there. But you also need to put all the prior result files (to which you want to append) there. If only one is missing this won't work! It seems that at least the .log file is missing or blocked.
The second question cannot be answered without having the complete input file. But, obviously, in the place where MICRESS expects the number of dissolved constituents, the keyword "anisotropic" is found which does not belong there! So, my guess is that simply the order of input is not correct!
Bernd
For your first question, I think the answer is that you can only "append" if all the result files are already there! As I understood, you created a new directory for the results and put "wd_results_6_restart" there. But you also need to put all the prior result files (to which you want to append) there. If only one is missing this won't work! It seems that at least the .log file is missing or blocked.
The second question cannot be answered without having the complete input file. But, obviously, in the place where MICRESS expects the number of dissolved constituents, the keyword "anisotropic" is found which does not belong there! So, my guess is that simply the order of input is not correct!
Bernd
Re: Weld solidification
Hi Bernd,
Thank you for your replay.
In case of secondary question, I have already checked the driving file again and again, but did not find some problems of input obviously. Here is the driv. file. Maybe there is subtle error which I missed. Please help! Thanks again!
And I am confused about the value of anisotropy coefficient. In User Guide Version 6.1_Running Micress, in the page 75 the sentence at the middle part shows a typical value of δ in cubic metal systems equals 0.05. But in the following picture the left one shows δ = 0.25. In addition, in case of Micress example, the values of these two anisotropy coefficient are about 0.2, or 0.3 or 0.4. However, in some papers for stainless steel, the value always is about 0.01. The order of magnitudes is different. I do not understand. Of course, I tried to input 0.01 but the dendrite morphology was very strange compared with the value 0.2. So, I want to ask the reason.
All the best,
Superabc
Thank you for your replay.
In case of secondary question, I have already checked the driving file again and again, but did not find some problems of input obviously. Here is the driv. file. Maybe there is subtle error which I missed. Please help! Thanks again!
And I am confused about the value of anisotropy coefficient. In User Guide Version 6.1_Running Micress, in the page 75 the sentence at the middle part shows a typical value of δ in cubic metal systems equals 0.05. But in the following picture the left one shows δ = 0.25. In addition, in case of Micress example, the values of these two anisotropy coefficient are about 0.2, or 0.3 or 0.4. However, in some papers for stainless steel, the value always is about 0.01. The order of magnitudes is different. I do not understand. Of course, I tried to input 0.01 but the dendrite morphology was very strange compared with the value 0.2. So, I want to ask the reason.
All the best,
Superabc
- Attachments
-
- wd_FeCrNi_Gamma_6_paper example_dri.txt
- driv. file
- (24.5 KiB) Downloaded 248 times
Re: Weld solidification
Hi superabc,
The error in your driving file is that you do not need to specify anisotropy data for phase interaction 2/2: For interactions between same phases there is no anisotropy model, just a misorientation model!
You can find out such errors in the input file by checking carefully what is requested in the output on screen and what is delivered in the input file: MICRESS already asks for number of dissolved constituents (concentration input), but the driving file still has the not needed data for anisotropy!
The difference in the order of magnitude of static anisotropy coefficients comes from the factor of 16 between anisotropy in
and in * (more details see here).
Bernd
The error in your driving file is that you do not need to specify anisotropy data for phase interaction 2/2: For interactions between same phases there is no anisotropy model, just a misorientation model!
You can find out such errors in the input file by checking carefully what is requested in the output on screen and what is delivered in the input file: MICRESS already asks for number of dissolved constituents (concentration input), but the driving file still has the not needed data for anisotropy!
The difference in the order of magnitude of static anisotropy coefficients comes from the factor of 16 between anisotropy in
Bernd
Re: Weld solidification
Hi Bernd,
Thank you for your suggestion.
I modified the driv. file. Yes, it can run but there are still two doubts.
1) The materials is SUS 304. Because what I simulate is always stainless steel, I just wanted to create one GES. file including liquid, fcc_a1, bcc_a2 and sigma for convenience. But in case of Micress, I just input first three phases. This time, when i run , the log. file showed dG= mocre than 13000j/cm**3, and dsf+ = 10.00 approximately. The value was very strange. I was confused for several hours. So, i just tried to create another GES. file including only liquid, fcc_a1 and bcc_a2 and used this one. Then, the physical values from log. file was correct. No matter the previous GES. fiel or latter GES. file, I just input same three phases in Micress, but the results were totally different. I do not know why.
2) Right now, at the beginning of running, it always showed phase 1 disappeared at ...time. I do not know which incorrect parameter affects this problem. Here i attached the driv. file and log. file.
I am looking forward to your advice.
Thank you for your suggestion.
I modified the driv. file. Yes, it can run but there are still two doubts.
1) The materials is SUS 304. Because what I simulate is always stainless steel, I just wanted to create one GES. file including liquid, fcc_a1, bcc_a2 and sigma for convenience. But in case of Micress, I just input first three phases. This time, when i run , the log. file showed dG= mocre than 13000j/cm**3, and dsf+ = 10.00 approximately. The value was very strange. I was confused for several hours. So, i just tried to create another GES. file including only liquid, fcc_a1 and bcc_a2 and used this one. Then, the physical values from log. file was correct. No matter the previous GES. fiel or latter GES. file, I just input same three phases in Micress, but the results were totally different. I do not know why.
2) Right now, at the beginning of running, it always showed phase 1 disappeared at ...time. I do not know which incorrect parameter affects this problem. Here i attached the driv. file and log. file.
I am looking forward to your advice.
- Attachments
-
- wd_results_6_log.txt
- (21.22 KiB) Downloaded 260 times
-
- wd_FeCrNi_Gamma_6_paper example_dri.txt
- driv.
- (24.8 KiB) Downloaded 246 times
Re: Weld solidification
Hi superabc,
Question 1 is not easy to answer as you did not show the corresponding .log files. But most probably you did an error when linking the phase numbers in the database to the numbers in MICRESS. Another possibility is that something went wrong when creating the .GES5 file - just redoing it would make sure that this was not the problem...
The second question seems clear: In the initial linearisation parameter of interface liquid/bcc_b2 which is written to the .log file, dG is positive, which means that the phase bcc_b2 is still not stable! So you just need to lower the initial temperature until it becomes stable. But keep in mind that you need some extra undercooling to overcome the curvature of the initial grain which can be quite high due to the high resolution of the simulation grid!
Furthermore, I would advise you to start with a smaller simulation domain until the simulation setup is correct - otherwise you will wait for hours just to see that there are more parameters to be adjusted!
Another point which attracted my attention is the definition of the diffusion coefficients: Why don't you use the full diffusion matrix ("multi") for fcc and bcc? I don't see a reason why to restrict the simulation in that respect...
Bernd
Question 1 is not easy to answer as you did not show the corresponding .log files. But most probably you did an error when linking the phase numbers in the database to the numbers in MICRESS. Another possibility is that something went wrong when creating the .GES5 file - just redoing it would make sure that this was not the problem...
The second question seems clear: In the initial linearisation parameter of interface liquid/bcc_b2 which is written to the .log file, dG is positive, which means that the phase bcc_b2 is still not stable! So you just need to lower the initial temperature until it becomes stable. But keep in mind that you need some extra undercooling to overcome the curvature of the initial grain which can be quite high due to the high resolution of the simulation grid!
Furthermore, I would advise you to start with a smaller simulation domain until the simulation setup is correct - otherwise you will wait for hours just to see that there are more parameters to be adjusted!
Another point which attracted my attention is the definition of the diffusion coefficients: Why don't you use the full diffusion matrix ("multi") for fcc and bcc? I don't see a reason why to restrict the simulation in that respect...
Bernd