New functionalities of TC-DICTRA - RWTH Aachen...
Transcript of New functionalities of TC-DICTRA - RWTH Aachen...
Thermo-Calc Software www.thermocalc.com
Aachen 12th of June 2003
New functionalities of TC-DICTRA
Thermo-Calc Anwendertreffen und SchulungAachen 11-13th of June 2003
Dr. Anders EngströmThermo-Calc Software
Stockholm Technology ParkSE-113 47 Stockholm, Sweden
Thermo-Calc Software www.thermocalc.com
Aachen 12th of June 2003
Outline
Introduction
Thermo-Calc Classic, version P
Thermo-Calc for Windows, TCW2.2
DICTRA, version 22
Programming interfaces
Databases
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History of Thermo-Calc
First version of Thermo-Calc was created in 1981. First sale was made in 1984. First sale of DICTRA somewhat later in 1994.
The team of researchers behind the software worked at the department of Physical Metallurgy at the Royal Institute of Technology
In the beginning the department was the base for development and distribution of the software packages.
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History of Thermo-Calc
To protect the software Thermo-Calc and DICTRA the researcher created a foundation
and donated their software rights to:
“Stiftelsen för Tillämpad Termodynamik”or
Foundation of Computational Thermodynamics(Current chairman: Bo Jansson)
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History of Thermo-Calc
In 1997 it was realised that the department was not suited to be the base of a sizable software operation and the foundation created the company:
”Thermo-Calc Software AB”
to take care of software maintenance, development and distribution.
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History of Thermo-Calc
Today Thermo-Calc Software is the exclusive distributor of the software with agents in USA, Germany, Japan, China and South America.
The foundation benefits from royalty payments which are used for grants to young researchers and to support of various projects in the filed of computational thermodynamics.
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Thermo-Calc Classic, version P
New features and commands in TDB, GES5, POLY3, POST, PARROT and ED_EXP modules
Modifications to some special modules, i.e. BIN, SCHEIL and POURBAIX
Improved documentation
Increased example collection
Improved graphics & 3D presentation
Some bugs have been corrected
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DATABASE_RETRIEVAL (TDB)
New Command: SET_AUTO_APPENDFor conveniently appending a database with the same system definition
Automatic conversion of database files for compatibility between Unix and PC/Windows
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GIBBS_ENEGRY_SYSTEM (GES5)
The maximum number of constituents in a non-ideal phase has been increased from 80 200. Ideal phases can have 1000 constituents.
Needed for solution phases with many associates or for aqueous solutions, in complex heterogeneous interaction systems.
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POLY_3Improved convergence in the commands:
COMPUTE_EQUILIBRIUM
COMPUTE_EQUILIBRIUM *
MAP and STEP somewhat modified
Possibility to check internal stability of phases using:STABILITY_CHECKin the SPECIAL_OPTIONS command
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POLY_3
Improvements in the command:COMPUTE_TRANSITION
Now possible to look for any new phase appearing when one conditions is varied
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TCP Example
Calculation of phase transitions in the alloy Ti-10Al-2V using COMPUTE_TRANSITION
Exploring the new graphics
Dumping diagrams
Using C-E *
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POLY_3Calculation of T0-temperatureThe temperature or composition where the two phases have the same Gibbs energy
γmGT
X
Gm
X
γ
α
T0-line
αmG
T=T0 for X=X1
X1This is usually regarded as the thermodynamic limit for a partitionless transformationImplemented in the SPECIAL_OPTIONS command and as an option in STEP
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POLY_3Calculation of paraequilibrium
% M
% C
γ
α
T0 . Paraequilibrium or partial equilibrium occur when one component in an alloy diffuse much faster than the others.
Conditions allow a partly partitionless transformation, where the new phase can form with different content of the mobile component, but with the same composition of the slow diffusing components.
Implemented in the SPECIAL_OPTIONS command and as an option in STEP
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POLY_3
γ
α
• •
% M
Iso-activity line for C in γ
Iso-activity line for C in α
Rapid transformation
Slow ν
fα fγ
% M
T0 .
Distance% C
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TCP Example
Calculation of a T0-line and a phase diagram according to paraequilibrium conditions for γto α transformations in a Fe-1.5Mn-0.3Si-Calloy
Also, we will calculate an isothermal section of a phase diagram for Fe-Mn-0.3Si-C and append a calculated diagram according to Paraequilibrium conditions
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POST
Conditions and database name are displayed in diagram when plotting
New command: CREATE_3D_PLOTFILECreates vrml-file (Virtual Reality Modelling Language) from tabulated data.
Makes it possible to view both squared, triangular and tetrahedral diagrams using one of many plug-ins freely available for web browsers.
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Example of VRML viewers for Internet Explorer and Netscape Navigator
For Windows and Mac:Cortona WRML Client from Parallelgraphicswww.parallelgraphics.com
For Windows, Linux and SIG IRIX 6.2:VRMLview from Systems in Motion (SIM) www.sim.no
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TCP Example
Calculate the “γ-volume” in the system Fe-Cr-C
Also, we will take a look at some liquidussurfaces as well as the “γ-volume” for the Fe-Cr-V-C system
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Edit-Experiments (ED_EXP)
Now possible to store and restore a weight set that records all the weights given to different experimental points in an assessment,using the new commands STORE_ALL_WEIGHTS and RESTORE_ALL_WEIGHTS.
It is also possible to list out all the calculated equilibrium points (using the LIST_ALL_EQUILIBRIA command) and to immediately calculate property diagrams with selective stepping options in which the calculations and the set stepping variable are based on a specific experimental point (using the GRAPHICS_PLOT command, which is identical to the STEP_WITH_OPTIONS command in the POLY module).
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TCW2
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TCW2.2
TCC version P DLL engine
Database information displayed on request
Possibility to append databases
Possibility to use functions in the post module
Improved show value feature
Improved MACRO management
Some other small improvements, e.g. re-entrant function
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TCW2.2 Example
Calculation of Pitting Resistance Equivalence (PRE) in a duplex stainless steel:
How to view database information
How to Append a database
How to change phase status
How to enter functions and tables
Exploring the show value feature
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Example: PRE in a duplex stainless steel
• PRE (Pitting Resistance Equivalence) is a empirical measure for corrosion resistance in stainless steels.
• One definition of PRE is:PRE=w%Cr+3,3*w%Mo+16*w%N
• For duplex stainless steels, it is desirable to have a high and balanced PRE-numbers in ferrite and austenite.
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DICTRA version 22
TCC version P thermodynamic engine
Larger workspaces to handle simulations with >10 elements
Possibility to simulate interfacial mobility controlled phase transformations. Achieved by adding a Gibbs-energy contribution to the growing phase
Model for diffusion in stoichiometric phases without any freedom, such as A2B
Numerical integration/differentiation of curves in the post processor
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Diffusion in stoichiometric phases
BCC
FCC +Al13Fe4
BCC +Al2Fe
Al2Fe
Al5Fe2
Al13Fe4
Fe-Al
Al 2F
e
Al 13
Fe4
FCCBCC
Al 5F
e 2
λ
µ∆∑ ><−==
jC
1j
'kjk LJ (Ågren)Model:
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Diffusion of C in Cementite (Fe3C)Experimental data from Ozturk et al. Experimental data from Schneider et al.
(Höglund, 2002)
Experimental information on the growth of cementite layers at different carbon activities
Mobility of C in cementite evaluated from this data
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Evaluation of mobility for C in Cementite
Mobility of C evaluated for each activity
The average mobility determined at each temperature
The logarithm of the mobility assumed to have a linear temperature dependency
Finally, the parameters M0 and Q in the expression below were assessed
RTQCemC eMM /
0−⋅=
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Solidification simulations
Equilibrium methods (lever-rule)Solute diffusion is rapid, i.e. complete solute back diffusion → uniform composition in both solids and liquid
Non equilibrium methods (SCHEIL)Negligible diffusion in solids, i.e. no solute back diffusion → solids retain same composition through solidification
Partial equilibrium methods (SCHEIC)Complete interstitial but negligible substitutional solute back diffusion
Moving phase boundary methods (DICTRA)Full integration of thermodynamics and kinetics
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Solidification simulations
Alloy:Fe- 5%Cr – 1%C – 2%V -8%W
Lever ruleSCHEIC
SCHEIL
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SCHEIC (SCHEil with Interstitial Carbon)
Basically a SCHEIL model for the substitutionalcomponents, with the addition that interstitial components are allowed to move freely among the liquid and all portions of the solid phases, so that their chemical potentials becomes equal everywhere throughout the whole system.
Status
TCS has developed an application program with the aid of the TQ interface.
Future
A separate module is planed to be available in TCQ and TCW 3.0
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Solidification simulations using DICTRA
Assumptions:
Assuming that equilibrium hold locally at the phase interface.Assumption regarding the geometry and size of the system, e.g. the interdendritic spacing.Assumption regarding the cooling rate.
However,
Full consideration of diffusion in both the liquid andsolid phases.
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DICTRA ExampleMicrosegregation during solidification:
Liquid
LiquidBccυ
LiquidBccυ
Fccυ
LiquidFccυ
Bcc
Fcc
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DICTRA Example cont.
Secondary dendrite arm spacing assumed to be 200 µm.
Cooling rate assumed to be 0.2 ºC/s.
λ/2
Temperature function:1780 – 0.2 • TIME
Liquidλ/2 =100 µm
Inactive phases
Bcc
Fcc
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Thermo-Calc Programming InterfacesNew Versions of:
TC-API (Thermo-Calc Application Programming Interface) For Windows programmingWritten in CAvailable for Windows and Linux environments
TQ-I (Thermodynamic Calculation Interface)Written in FORTRANAvailable for all UNIX dialects and Windows.
TC-Toolbox in MATLAB® Available for Windows.
All new versions based on Thermo-Calc version P
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TQ-I version 4.0
Now also possible to calculate kinetic coefficients, e.g. atomic mobilities, tracer diffusion, chemical diffusion and intrinsic diffusion coefficients All syntaxes the same as in DICTRA, e.g.
M(Phase,J) Mobility coefficient where J=diffusing specie
DT(Phase,J) Tracer diffusion coefficient where J=diffusing specie
DC(Phase,J,K,N) Chemical diffusion coefficient whereK=gradient specie, and N=reference specie
DI(Phase,J,K,N) Intrinsic diffusion coefficient
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TCFE3
Thermo-Calc Software Steel database version 3
Update of TC-FE2000
Released with TCC version P
For Fe-rich alloys with the alloying elements:
Al-B-C-Co-Cr-Cu-Mg-Mn-Mo-N-Nb-Ni-O-P-S-Si-Ti-V-W
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TCFE3Improvements:
Improved data for sigma phase in stainless steel.Data added in the Nb-Ni, Fe-Cr-Mo and Cr-Mo-Ni systems.
Improved data for the Ti(C,N) fcc-carbonitride.
Improvements in starting values.
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TCFE3Comparison to experimental liquidus data for low alloy steels, tool steels and stainless steels
Liquidus
1350
1375
1400
1425
1450
1475
1500
1525
1550
1350 1375 1400 1425 1450 1475 1500 1525 1550
Experimental value
Calc
ulat
ed v
alue
Data from: Jernkontoret ” A Guide to the Solidification of Steels”
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TCFE3
Solidus
1100
1200
1300
1400
1500
1100 1200 1300 1400 1500
Experimenta l va lue
Cal
cula
ted
valu
e
Comparison to experimental solidus data for low alloy steels, tool steels and stainless steels
Data from:Jernkontoret ” A Guide to the Solidification of Steels”, where a cooling rate of 0.1°C/s was used
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TCFE3
C h ro m iu m co n te n t in Au ste n ite (m ass-% )
0
5
10
15
20
25
30
0 5 10 15 20 25 30
Ex p e rim e n ta l va lu e
Cal
cula
ted
valu
e
Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels
Data from:S.M. Wessman et al., EC Report EUR20315 EN
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TCFE3Comparison to experimental equilibrium austenite composition in different multicomponent, multiphase stainless steels
M olybde num conte nt in Fe rrite (mass-%)
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Experimental value
Cal
cula
ted
valu
e
Data from:S.M. Wessman et al., EC Report EUR20315 EN
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TCFE3Comparison to experimental equilibrium fractions of ferrite and sigma-phase for a duplex stainless steel as a function of temperature
α
σ
Data from:J.-O. Nilsson, P. Kangas, T. Karlsson and A. Wilson, Metall. Mater. Trans. A 31A, (2000), 35.