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How to create tdb files Alan Dinsdale, Sandy Khvan “Thermochemistry of Materials” SRC

How to create tdb files Alan Dinsdale, Sandy Khvan “Thermochemistry of Materials” SRC NUST, MISiS , Moscow, Russia. What are tdb files ?. TDB files contain thermodynamic data necessary for calculating phase diagrams They can contain data for a single or multiple systems

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How to create tdb files Alan Dinsdale, Sandy Khvan “Thermochemistry of Materials” SRC

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  1. How to create tdb files Alan Dinsdale, Sandy Khvan “Thermochemistry of Materials” SRC NUST, MISiS, Moscow, Russia

  2. What are tdb files ? • TDB files contain thermodynamic data necessary for calculating phase diagrams • They can contain data for a single or multiple systems • Generally they are used in conjunction with ThermoCalc although other software may be able to read them (with some restrictions)

  3. General comments • Always try to document your tdb files • Date • Author • Source of the data • Uncertainties about parameters or choice of models • Remember that you may want to look at tdb files you created 5 years ago, or someone else may want to use them

  4. Resources • ThermoCalc User Guide has a very comprehensive description • Other tdb files • Unary.tdb has data for the elements

  5. Structure • The tdb format is very flexible • Can be very confusing and difficult to understand • ThermoCalc will assume missing parameters are zero • Length of lines limited to 80 characters • Good practice: • Keep data for a phase or a system together • Do include parameters which have a zero value • Avoid default values for minimum and maximum temperatures

  6. $ Comments $ Use this area to indicate where the data come from $ Elements used ELEMENT AG FCC_A1 1.0787E+02 5.7446E+03 4.2551E+01 ! $ Species if your data are expressed in non elemental entities SPECIES AL2O3 AL2O3 ! $ Phases – the number of sublattices PHASE HALITE % 2 1 1 ! $ Constituents – which elements or species are on which sublattices PHASE FCC_A1 ( 2 1 1 ! CONSTITUENT FCC_A1 : AG,CU,GE : C,VA : ! $ Functions – useful but not strictly necessary FUNCTION GHSERGE 298.15 -9486.153+165.635573*T-29.5337682*T*LN(T)+5.568297E-3*T**2-1.513694E-6*T**3 +163298*T**(-1); 900 Y -5689.239+102.86087*T-19.8536239*T*LN(T)-3.672527E-3*T**2; 1211.4 Y -9548.204+156.708024*T-27.6144*T*LN(T)-859.809E26*T**(-9); 3200 N ! $ Data PARAMETER G(BCC_A2,FE:VA;0) 298.15 GHSERFE; 6000 N ! PARAMETER L(LIQUID,AG,MG;0) 298.15 -68930.725+0.684874*T; 3000 N !

  7. Comments • Comment lines begin with $ • Use them ! • Best to start non comment lines with a space

  8. Elements • Need to include these lines if you want to do mass based calculations ELEMENT /- ELECTRON_GAS 0.0000E+00 0.0000E+000.0000E+00 ! ELEMENT VA VACUUM 0.0000E+00 0.0000E+000.0000E+00 ! ELEMENT AG FCC_A1 1.0787E+02 5.7446E+03 4.2551E+01 ! ELEMENT AL FCC_A1 2.6982E+01 4.5773E+03 2.8322E+01 ! ELEMENT AM DHCP 2.4306E+02 0.0000E+00 0.0000E+00 ! ELEMENT AS RHOMBOHEDRAL_A7 7.4922E+01 0.0000E+00 0.0000E+00 ! ELEMENT AU FCC_A1 1.9697E+02 6.0166E+03 4.7488E+01 ! ELEMENT B BETA_RHOMBO_B 1.0811E+01 1.2220E+03 5.9000E+00 ! Most statements are terminated with ! S298 Relative Atomic Mass (Atomic Weight) Standard Element Reference Phase H298-H0 • You can also copy the relevant lines from the unary database

  9. Species • You need to identify SPECIES if your models involve non-elemental constitutentsegCaO, SiO2, O2, SO2, H2 SPECIES AL2O3 AL2O3 ! SPECIES Silica SI1O2 ! SPECIES FE+2 FE/+2 ! SPECIES SB-3 SB/-3 ! Species name Formula in terms of the defined elements. Note /+ and /- for charge

  10. Phases • These lines define which phases you want to use, describe the number of sublattices and how many sites there are on each sublattice PHASE BCT_A5 % 1 1 ! PHASE GAS % 1 1 ! PHASE HALITE % 2 1 1 ! PHASE SIGMA % 3 8 4 18 ! Phase name Number of sites on each sublattice Special set of characters Number of sublattices

  11. Type definition • Extra information about the phase • Magnetic information • Chemical ordering • Makes use of this special symbol in PHASE definition PHASE BCC_A2 B 2 1 3 ! PHASE FCC_A1 A 2 1 1 ! PHASE FCC_L12 AY 3 .75 .25 1 ! TYPE_DEF C GES AM_PH_DES @ COMP_SETS 2,,,,,,,, ! TYPE_DEF A GES AM_PH_DES @ MAGNETIC -3 0.280, ! TYPE_DEF Y GES AM_PH_DES FCC_L12 DISORD FCC_A1 ,,, ! TYPE_DEF B GES AM_PH_DES @ MAGNETIC -1 0.400, !

  12. Constituents • Indicates which species go on which sublattices PHASE FCC_A1 ( 2 1 1 ! CONSTITUENT FCC_A1 : AG,CU,GE : C,VA : ! PHASE SIGMA % 3 8 4 18 ! CONSTITUENT SIGMA : AL,CO,FE : MO,TI: AL,CO,FE,MO,TI : !

  13. Functions • Can be used to • refer to standard data eg for the elements GHSERFE, GLIQGE or • Data which you might want to manipulate • The format is: Lower temperature limit Function name Upper temperature limit, yes there is another range FUNCTION GHSERGE 298.15 -9486.153+165.635573*T-29.5337682*T*LN(T)+5.568297E-3*T**2-1.513694E-6*T**3 +163298*T**(-1); 900.00 Y -5689.239+102.86087*T-19.8536239*T*LN(T)-3.672527E-3*T**2; 1211.40 Y -9548.204+156.708024*T-27.6144*T*LN(T)-859.809E26*T**(-9); 3200.00 N ! ; ends each range of data Upper temperature limit, no more ranges

  14. Syntax of data lines is very simple • Negative powers of T within brackets eg T**(-9) • LOG and LN are the same • Functions can call other functions

  15. Parameters • Similar to functions • Used for Gibbs energy (G), Interactions (G or L), Curie temperature (TC) and the magnetic moment (BMAGN or BM) FUNCTION GHSERFE 298.15 1225.7+124.134*T-23.5143*T*LN(T)-4.39752E-3*T**2-0.058927E-6*T**3 +77359*T**(-1); 1811 Y -25383.581+299.31255*T-46*T*LN(T)+2296.03E28*T**(-9); 6000.00 N ! PARAMETER G(BCC_A2,FE:VA;0) 298.15 GHSERFE; 6000 N ! PARAMETER TC(BCC_A2,FE:VA;0) 298.15 1043; 6000 N ! PARAMETER BM(BCC_A2,FE:VA;0) 298.15 2.22; 6000 N ! PARAMETER G(SIGMA,FE:CR:CR;0) 298.15 8*GFCCFE+22*GHSERCR+92300-95.96*T; 6000 N !

  16. Interactions • Each line indicates a different term in the Redlich-Kister power series expression • The order of the parameter is given by the number after the semicolon ie. 0 refers to the regular solution parameter, 1 to the subregular term etc of the Redlich – Kister expression • It is possible to miss lines out if the parameter is zero; however it is much clearer if you give the parameter explicitly PARAMETER L(LIQUID,AG,MG;0) 298.15 -68930.725+0.684874*T; 3000 N ! PARAMETER L(LIQUID,AG,MG;1) 298.15 16824.411-4.430152*T; 3000 N ! PARAMETER L(LIQUID,AG,MG;2) 298.15 1928.379-1.977574*T; 3000 N ! PARAMETER L(LIQUID,AG,MG;3) 298.15 -2624.584-2.440899*T; 3000 N ! Best if these are in alphabetical order

  17. Phase with sublattices • The parameter description used a colon to separate the sublattices • PARAMETER G(BCC_A2,FE:VA;0) 298.15 GHSERFE; 6000 N ! • PARAMETER L(AL8MN5_D810,SI:MN:AL,MN;0) 298.15 0; 6000 N !

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