efficient phase diagram information from computational ... · clearly defined module for gibbs...
TRANSCRIPT
Open CalphadSoftware and Databases
Ursula R. Kattner1, Bo Sundman2, Mauro Palumbo3, Suzana G. Fries3
1National Institute of Standards and Technology, Gaithersburg, MD, USA
2INSTN CEA, Saclay, France3ICAMS, STKS, Ruhr University Bochum, Bochum, Germany
CALPHAD XLRio de Janeiro, Brazil
May 27, 2011
Early CALPHAD Software
1970 L. Kaufman and H. Bernstein: Computer programs listed in Appendix 1 & 2 of “Computer Calculation of Phase Diagrams”
Distributed Source Code:1971 G. Eriksson – SOLGAS1975 G. Eriksson – SOLGASMIX1977 H.L. Lukas – BINGSS, BINFKT, TERGSS and
TERFKT1981 H.L. Lukas – QUAGSS, QUAFKT and PMLFKTLeased and Licensed Programs:1976 McGill & École Polytechnique – F*A*C*T 1981 KTH – Thermo-Calc (Poly)Plus a variety of other programs
Development of Thermodynamic Databases in the 1980s
Thermodynamic assessments of binaries and ternaries using
Trial and errorLukas optimizer programs (BINGSS, TERGSS), 1977Thermo-Calc’s Parrot, 1984
Multicomponent databases in their infancyCollection of descriptions at KTH as “solution” databaseDatabases for salt and slag/oxide systems at École Polytechnique
Development of improved thermodynamic models to take into account
Short range order in liquidsLong range order in intermetallic compounds
Free Software Impact in the 1980s
Laid foundation for CALPHAD methodEnabled testing of models
not all models programmed “survived”
Enabled assessment of thermodynamic descriptions of binary and ternary systemsLaid foundation for multicomponent databasesLaid foundation for success of commercial software
Currently Available CALPHAD Software
CATCalcpressure (modified Jacobs-Oonk)order/disorder (modified CEF)
FactSageliquid (modified quasichemical)aqueous (Pitzer, Helgeson)pressure (Birch-Murnaghan)
MatCalcother models ?
MTDATAaqueous, other models ?
Pandatorder/disorder (CSA)
Thermo-Calcorder/disorder (modified CEF, binary tetrahedron CVM)liquid oxides (Kapoor-Frohberg-Gaye)aqueous (SIT, Pitzer, revised Helgeson-Kirkham-Flowers)pressure (Murnaghan, modified Jacobs-Oonk)
All:• Commercial• General sublattice model
allowing multi-atomic species with polynomial for temperature dependence and Hillert-Jarl for magnetic contribution
• Optimization module
CALPHAD Thermodynamic Databases
General Alloys and Pure SubstancesFACT, SGTE
Fe-Alloys and SteelsCompuTherm, FactSage, Thermo-Calc , ThermoTech
Ni-Alloys (Superalloys)CompuTherm, NIST, Thermo-Calc, ThermoTech
Light Metal AlloysCompuTherm, COST507, FactSage, NPL, Thermo-Calc, ThermoTech
SoldersCOST531, NIST-Sn, NPL, Tohoku University
Nuclear MaterialsThermo-Calc/AEAT, Thermodata
Many more databases exist, butDatabases are not likely to be available/compatible for all software packages
Since the 1990s: Coupling with Other Programs
Casting simulationsDiffusion Simulations
DICTRA• Sharp interface
Phase field• Diffuse interface
Property calculationsDTA simulations
Direct coupling via programming interfacesIndirect coupling via look-up tables
Integrated Computational Materials Engineering (ICME)
Free Software Impact since the 1990s
Enabled proof of concept for coupling of CALPHAD with engineering software
Lukas based code was implemented in the casting simulation programs ProCast in the late 1990s Has been replaced since by a commercial CALPHAD program
Guo and Samonds (Modeling of Casting & Solidification Processes 2004, Taiwan):Solidification of an IN713 alloy
Primary dendrite arm spacing (cm)
Volume fraction of γ’
Yield strength (MPa)
Average γ’ particle radius (nm)
Limitations of Commercial Packages
Commercial packages only available as executables or programming librariesChoice of software package determines the availability of modelsChoice of software package determines available thermodynamic databasesPredetermined data type that can be obtained from the thermodynamic calculation
User cannot implement and test new models!Potential for delaying future improvements of the CALPHAD method
Wish List for Free CALPHAD Software
Compatible with most common data file formatsGeneral sublattice model and other major modelsDocumentation of program codeClearly defined module for Gibbs energy modelsClearly defined module for Gibbs energy minimization and phase equilibria calculations
phase stability testingglobal minimization
Stepping and mappingUser interfaces for input and outputOptimizer for thermodynamic descriptionsInterfaces for coupling with other programs
Current Freely Available CALPHAD Programs
Lukas’ programsUncommon file format for databaseNot all commonly used models availablePrimitive user interface requires expert userNo phase stability testing
SolCalc (modified Lukas PMLFKT)Uncommon file format for databaseCommonly used models availableUser interface customized for solidification calculations
Gibbs (E. Garcia, A. Powell III, R. Arroyave)File format compatible with common database format (TDB)Very limited choice of modelsIntuitive user interface
Short in fulfilling the wish list
Where to Begin New CALPHAD Software?
1. General sublattice model and other major models2. Compatible with most common data file formats3. Clearly defined module for Gibbs energy models4. Clearly defined module for Gibbs energy minimization
and phase equilibria calculationsphase stability testingglobal minimization
5. Documentation of program code6. User interfaces for input and output7. Optimizer for thermodynamic descriptions8. Program interfaces for coupling with other programs
Module for Gibbs Energy Models
Commonly used modelsRegular solution type, sublattice models (regular, order/disorder, ionic liquid), associate model, …
Reads unencrypted TDB files (Thermo-Calc database format)Maintains link between phases and their Gibbs energy functionsProvides values of the Gibbs energy and its derivatives to other program modules
FTMP (Free Thermodynamic Model Package)
Parameter Records Inside FTMP
Quantities obtained from FTMP
Module for Gibbs Energy Minimization
Handles phases with internal equilibriumMinimizes Gibbs energy of the system for a variety conditions
Phase fieldsPhase boundariesInvariant equilibria, extremaSpecial conditions (fixed μ, …)
Calculates driving force of phases not included in current equilibrium calculation
modify EQCALC from Lukas’ PMLFKT
Module for Stability Testing
Translates user input into conditions for Gibbs energy minimizationDetermines set of phases with lowest Gibbs energyDetects invariant equilibrium and extrema
modify PD_LEVER from SolCalc= (suite of solidification programs)
Test Programs
Programs needed for testing modulesMinimal programming effortReplace corresponding original code with new codeRun test calculations and compare results with existing programs
PMLFKTTest equilibrium calculationsTest basic stepping
SolCalc (Lever, Scheil)Test stepping with stability testing
Results of original PMLFKT and SolCalc were verified by comparison with other calculations: BINFKT, Mathematica, Thermo-Calc
Results from Test Programs
PMLFKT: reproduce isothermal 1223 K section of Cr-Fe-Mo
SolCalc (Lever, Scheil): reproduce solidification paths for Ni-Al-Ta
Auxiliary Programs
Are needed to prepare parameters of new models for testingDebye and Einstein models for heat capacity not available in any CALPHAD software, free or commercialLukas UNIGSS was developed to obtain Gibbs energy parameters for unary systems
Only for functions with linear parameters
Extend UNIGSS for Debye/Einstein model heat capacities
Mauro Palumbo’s talk
Open CALPHAD Databases
Database Material Last Update
Kaufman superalloys 1991
COST507 light metal alloys 1998
Zircobase Zr-based alloys 1999
NIST-Ni superalloys 2002
NIST-NiMob superalloys (diffusion) 2008
NIST-Sn solders 2004
SGTE-Unary pure elements 2001
BUT: Usually no updates after completion of project for which database was developed!
Commercial and Free Software
Commercial SoftwareCustomer supportConsulting servicesNo need to be a CALPHAD expertWell suited for application in engineering environmentsImplementation of new models driven by customer demands
Free SoftwareFlexibilityNeed to be an expert in thermodynamics and CALPHAD modelingWell suited for academic research environmentsImplementation of new models driven by scientific interestsCannot use commercial databasesMay attract large materials science community unfamiliar with CALPHAD
Commercial and Free Databases
Commercial DatabasesCustomer supportFine tuned for specific materialExtensively verifiedRegular updates
Free DatabasesSupport not certainAlthough developed for a specific material fequently more general with limited fine tuningVerification may be limitedNo regular updates
Concluding Thoughts
Will free CALPHAD software and databases negatively impact the market for commercial packages?
Different customers have different expectationsFree CALPHAD software always existed since the birth of CALPHADCompanies providing CALPHAD software and databases are too small to carry out heavy research projects, such as implementing and testing of new modelsAvailability of source code is needed for implementation and testing of new modelsFree software and databases are not really free, the tax payer usually paid for them
Open Source CALPHAD = OpenCalphad
Enables advancement of new CALPHAD models and their testing without the necessity of having to reinvent the wheel.
OpenCalphad is a registered web siteBulletin board later this yearSome experienced Calphaders will be invited for testing
Acknowledgement