Mixed input (manual, global) for diffusion data
Posted: Fri Sep 24, 2021 6:09 pm
Dear Bernd,
I am working with additively manufactured (LPBF) MPEAs trying to simulate solidification microstructure under different thermal conditions in order to investigate microstructure evolution. Yet I have a quite big limitation; I don't have a mobility database for my alloy system. I assume even under fast solidification velocities, not having a proper input would deviate segregations and thus the morphology of solidified state (e.g. wrong eutectic morphologies and etc.)
I am mainly working with two different compositions, one solidifies in single phase FCC and other solidifies in FCC-B2 phases. I coupled my custom thermodynamic database with one of the MOBFE databases to use diffusion data for FCC. Besides, I thought that I can enter the diffusion constants for diffusion of individual elements in liquid (in the order of 10E-5) manually by using diagonal d, and also activation energies and pre-exponential factors for diffusion in B2-NiAl phase, so that it can calculate temperature dependent diffusion coefficients. In my case, however, the B2 phase is non stoichiometric NiAl (there is also solubility of other elements), but the activation energies and pre-exponential factors I entered is for diffusion in Ni48Al52 (stoichiometric) for 900 to 1200°C range , since it was the best I can find from literature;
# How shall diffusion of component CO in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.00000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component CO in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component CO in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
3500
# Activation energy? (real) [J/mol]
346610
# How shall diffusion of component NI in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.0000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component NI in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component NI in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
1400
# Activation energy? (real) [J/mol]
346630
# How shall diffusion of component AL in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.00000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component AL in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component AL in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2300
# Activation energy? (real) [J/mol]
339710
# How shall the interval for updating diffusion coefficients
# data be set?
# Options: constant from_file
constant
# Interval for updating diffusion coefficients data? [s]
0.1
# Concentration solver
# --------------------
# Factor for diffusion time stepping? (0.0 < factor < 1.0)
0.95000
#
# List of phases and components which are stoichiometric:
# phase and component(s) numbers
# List of concentration limits (at%):
# <limits>, phase number and component number
# List of penalty conditions:
# <penalty>, phase 1, phase2, component number
# List for ternary extrapolation (2 elements + main comp.):
# <interaction>, component 1, component 2
# Switches: <stoich_enhanced_{on|off}> <solubility_{on|off}>
# List of relative criteria on phase composition
# <criterion_higher | criterion_lower>, phase No 1, phase No 2, component No
# List of sublattice order conditions:
# <ordered|disordered>, phase , sublattice 1, sublattice 2
# List of source changes for diffusion data
# <switch_diff_data>, Phase-No., reference phase
# Switch: Add composition sets for calculation of diffusion/volume/enthalpy data
# <diff_comp_sets | vol_comp_sets | enth_comp_sets>, phase list
# End with 'no_more_stoichio' or 'no_stoichio'
diagonal
no_stoichio
My question is, do you think this approach can somehow work? Do you have any recommendations on how to do a workaround?
Regards,
I am working with additively manufactured (LPBF) MPEAs trying to simulate solidification microstructure under different thermal conditions in order to investigate microstructure evolution. Yet I have a quite big limitation; I don't have a mobility database for my alloy system. I assume even under fast solidification velocities, not having a proper input would deviate segregations and thus the morphology of solidified state (e.g. wrong eutectic morphologies and etc.)
I am mainly working with two different compositions, one solidifies in single phase FCC and other solidifies in FCC-B2 phases. I coupled my custom thermodynamic database with one of the MOBFE databases to use diffusion data for FCC. Besides, I thought that I can enter the diffusion constants for diffusion of individual elements in liquid (in the order of 10E-5) manually by using diagonal d, and also activation energies and pre-exponential factors for diffusion in B2-NiAl phase, so that it can calculate temperature dependent diffusion coefficients. In my case, however, the B2 phase is non stoichiometric NiAl (there is also solubility of other elements), but the activation energies and pre-exponential factors I entered is for diffusion in Ni48Al52 (stoichiometric) for 900 to 1200°C range , since it was the best I can find from literature;
# How shall diffusion of component CO in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.00000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component CO in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component CO in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
3500
# Activation energy? (real) [J/mol]
346610
# How shall diffusion of component NI in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.0000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component NI in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component NI in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
1400
# Activation energy? (real) [J/mol]
346630
# How shall diffusion of component AL in phase LIQUID be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2.00000E-05
# Activation energy? (real) [J/mol]
0.0000
# How shall diffusion of component AL in phase A1_FCC be solved?
multi ggg
# How shall diffusion of component AL in phase B2_BCC be solved?
diagonal d
# Diff.-coefficient:
# Prefactor? (real) [cm**2/s]
2300
# Activation energy? (real) [J/mol]
339710
# How shall the interval for updating diffusion coefficients
# data be set?
# Options: constant from_file
constant
# Interval for updating diffusion coefficients data? [s]
0.1
# Concentration solver
# --------------------
# Factor for diffusion time stepping? (0.0 < factor < 1.0)
0.95000
#
# List of phases and components which are stoichiometric:
# phase and component(s) numbers
# List of concentration limits (at%):
# <limits>, phase number and component number
# List of penalty conditions:
# <penalty>, phase 1, phase2, component number
# List for ternary extrapolation (2 elements + main comp.):
# <interaction>, component 1, component 2
# Switches: <stoich_enhanced_{on|off}> <solubility_{on|off}>
# List of relative criteria on phase composition
# <criterion_higher | criterion_lower>, phase No 1, phase No 2, component No
# List of sublattice order conditions:
# <ordered|disordered>, phase , sublattice 1, sublattice 2
# List of source changes for diffusion data
# <switch_diff_data>, Phase-No., reference phase
# Switch: Add composition sets for calculation of diffusion/volume/enthalpy data
# <diff_comp_sets | vol_comp_sets | enth_comp_sets>, phase list
# End with 'no_more_stoichio' or 'no_stoichio'
diagonal
no_stoichio
My question is, do you think this approach can somehow work? Do you have any recommendations on how to do a workaround?
Regards,