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