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ModelAppendXTDB.XTDB
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<Models>
<!-- This is a tag with short explanation of XTDB model tags and their attributes.
The Configuration attribute in the Phase tag specify configurational entropy.
The Model tag should be included in the XTDB file or appear in an AppendXTDB tag in an XTDB file.
The list of Model tags here is mainly descriptive. Some of them should be included in a Defaults tag and
thus apply to the whole database, some inside a phase tag. Several Model tags define one or more
Model Parameter IDentifiers (MPID) used for parameters in the models to describe a composition dependent
contributions to the Gibbs energy of a phase, for example from magnetism.
An MPID can describe how a property, for example the Curie T, varies with the composition and
sometimes T or P. If a software reading an XTDB file finds a parameter with an MPID for a known model
it will know how to handle this.
The software reading the database should check if the models used in the database are implemented and
check that the MPID for the models the database correspont to its internal set of MPID.
There may be more models specified here than actually used in the database. But if the software
finds a model not implemented or an unkown MPID when extracting data for a phase
it should issue an error or warning.
The AmendPhase tag is nested inside a Phase tag and is Models attribute can specify several Model Id
which define additional models with MPID for the phase.
A DisorderedPart tag must be nested separately inside the Phase tag
as it has additional phase dependent information.
A TenaryXpol tag must be used for each ternary which does not have the default ternary extrapolation,
together with the model parameters for the binaries together with the phase attribute.
Phases with many sublattices may have a wildcard, denoted as "*" as constituent in some sublattices.
A wildcard means the parameter is independent of the constituent in the sublattices with wildcards.
Such parameters should not be merged with parameters with explicit constituents on the sublattices.
The EEC tag is global for the whole database if included in the Defaults tag.
Some model tags, attributes and MPIDs below are tentative and open for discussion and new can be added.
Some attributes of the tags are optional.
More model tags with references to papers describing the model can be added when needed.
These should be communicated with other software developers.
-->
<Magnetic Id="IHJBCC" MPID1="TC" MPID2="BMAGN" Bibref="82Her" >
<!-- Add a magnetic Gibbs energy according to Inden-Hillert-Jarl to a BCC phase as
G=f(TAO)*LN(BMAGN+1) where TAO=T/TC.
TC is a combined Curie/Neel T and BMAGN the average Bohr magneton number, both depend on composition
Negative TC is divided by -1, the anti-ferromagnetic factor.
f_below_TC= +1 -0.905299383*TAO**(-1) -0.153008346*TAO**3-.00680037095*TAO**9
-0.00153008346*TAO**15; and
f_above_TC= -0.0641731208*TAO**(-5) -0.00203724193*TAO**(-15)
-0.000427820805*TAO**(-25);
-->
</Magnetic>
<Magnetic Id="IHJREST" MPID1="TC" MPID2="BMAGN" Bibref="82Her" >
<!-- Add a magnetic Gibbs energy according to Inden-Hillert-Jarl to an FCC or other non-BCC phases as
G=f(TAO)*LN(BMAGN+1) where TAO=T/TC.
TC is a combined Curie/Neel T and BMAGN the average Bohr magneton number, both depend on composition.
Negative TC is divided by -3, the antiferromagnetic factor.
f_below_TC= +1-0.860338755*TAO**(-1) -0.17449124*TAO**3 -0.00775516624*TAO**9
-0.0017449124*TAO**15; and
f_above_TC= -0.0426902268*TAO**(-5) -.0013552453*TAO**(-15)
-0.000284601512*TAO**(-25);
-->
</Magnetic>
<Magnetic Id="IHJQX" MPID1="CT" MPID2="NT" MPID3="BMAGN" Bibref="01Che 12Xio" >
<!-- Add a magnetic Gibbs energy to a any phase as
G=f(TAO)*LN(BMAGN+1) where the positive value of TAO=T/CT or T/NT.
CT is the Curie T, NT is the Neel T and BMAGN the effective Bohr magneton number.
There is no antiferromagnetic factor and only positive CT ot NT values should be used.
f_below_TC= +1-0.842849633*TAO**(-1) -0.174242226*TAO**3 -0.00774409892*TAO**9
-0.00174242226*TAO**15 -0.000646538871*TAO**21; and
f_above_TC= -0.0261039233*TAO**(-7)c-0.000870130777*TAO**(-21)
-0.000184262988*TAO**(-35)c-6.65916411E-05*TAO**(-49);
-->
</Magnetic>
<Einstein Id="GEIN" MPID1="LNTH" Bibref="01Che" >
<!-- Add a Gibbs energy due to the Einstein low T vibrational model,
G=1.5*R*exp(LNTH)+3*R*T*LN(1-exp(-exp(LNTH)/T)).
LNTH is the logarith of a fitted Einstein T in Kelvin, with the value LN(THETA).
The heat capacity of an element or compound can be fitted with several THETA values
but only one of these can be composition dependent. The others are used in GEIN function
in the Gibbs energy model parameter. The reason to use the logarithm of THETA is that
it is physically more reasonable to vary the logarithm with the composition.
-->
</Einstein>
<Liquid Id="Liquid2State" MPID1="G2" MPID2="LNTH" Bibref="88Agr 13Bec" >
<!-- Unified model for the liquid and the metastable low T amorphous state treated as an Einstein solid.
The G2 parameter describes the stable liquid and the transition to the amorphous state and
LNTH is the logarithm of the Einstein THETA for the amorphous phase.
See the reference for details.
-->
</Liquid>
<Volume Id="VlowP1" MPID1="V0" MPID2="VA" MPID3="VB" Bibref="05Lu" >
<!-- The volume of a phase as function of T and moderate P and constitution via the model parameters:
V0 is the volume at the reference T and P, VA is the integrated thermal expansion at 1 bar
and VB is the isothermal compressibilty at 1 bar.
There can be several volume models in the database and software as for magnetism.
-->
</Volume>
<DisorderedPart Disordered="x" Sum="y" Subtract="z" Bibref="97Ans 07Hal" >
<!-- This tag must appear explicitly inside the ordered phase tag as the attributes depend on the phase.
It is often used for phases with many sublattices that does not disorder.
If the parameters for the disordred part are in a separate phase that phase Id "x" must be specified
in the Disordered attribute.
The Disordered attribute is not needed if model parameters for the disordered part use the same phase Id
as the ordered phase but with a single sublattice for the ordered sublattices.
The Sum attribute "y" is the number of ordering sublattices with identical constituents
to be added together to calculate the average disordered composition.
The Gibbs energy is calculated separately for the ordered and disordered model
parameters and added together.
If the Subtract attribute is provided the Gibbs energy for the ordered part is calculated
twice, the second time with disordered fractions, and subtracted.
The configurational Gibbs energy is calculated only for the ordered phase.
-->
</DisorderedPart>
<Permutations Id="FCC4Perm" Bibref="09Sun" >
<!-- An FCC phase with 4 sublattices for the ordered tetrahedron can use the Id of this model
in the AmendPhase tag to indicate that parameters with permutations of the same set of constituents
on identical sublattices are included only once in the database and must be permuted by software.
With only nearest neighbour parameters it can be used also for HCP.
-->
</Permutations>
<Permutations Id="BCC4Perm" Bibref="09Sun" >
<!-- A BCC phase with 4 sublattices for the ordered asymmetric tetrahedron use the Id of this model
in the AmendPhase tag to indicate that parameters with permutations of the same set of constituents
on identical sublattices are included only once in the database and must be permuted by software.
-->
</Permutations>
<EEC Id="EEC" Bibref="20Sun" >
<!-- The Equi-Entropy Criterion (EEC) means that the software must ensure any solid phases
with higher entropy than the liquid phase must not be stable. It must be used in the Defaults
as it applies to the whole system and the liquid phase must have an "L" as the State attribute.
-->
</EEC>
<TernaryXpol Phase="x" Constituents="A B C" Xmode="ijk" Bibref="01Pel" >
<!-- This is a tag that must be used explitly for each ternary extrapolation of the binary parameters
which does not have the default ternary extrapolation method. There can be 3 different methods
for each ternary.
The Constituent tag must specify 3 constituents, A B C, separated by one or more spaces.
The Xmode attribute specifies the ternary extraplation of the 3 binaries, A-B, A-C and B-C.
If M the Muggianu extrapolation, if K the Kohler extrapolation and if T the Toop extrapolation.
For the Toop one must also specify which of the binary constituents is the Toop element.
For example Xmode="KT3T3" means the binary A-B extrapolate as Kohler,
A-C and B-C extrapolate as Toop with the third constituent as Toop element .
-->
</TernaryXpol>
<EBEF Id="EBEF" Bibref="18Dup" >
<!-- The Effective Bond Energy Formalism for phases with multiple sublattices using wildcards, "*",
in the endmember parameters indicating sublattices with irrelevant constituents.
The phase must also use the Disordered_2Part model for the reference state of the elements.
There is a proposal that the parameters may also use a short form "constituent@sublattice"
in order to specify only the constituents in sublattices without wildcards.
-->
</EBEF>
<Bibliography>
<!-- This is the bibliography for the models -->
<Bibitem Id="82Her" Text="S. Hertzman and B. Sundman, A Thermodynamic analysis of the Fe-Cr system,'
Calphad, Vol 6 (1982) pp 67-80" />
<Bibitem Id="88Agr" Text="J. Agren, Thermodynmaics of supercooled liquids and their glass transition,
Phys Chem Liq, Vol 18 (1988) pp 123-139" />
<Bibitem Id="97Ans" Text="I. Ansara, N. Dupin, H. L. Lukas and B. Sundman, Thermodynamic assessment
of the Al-Ni system, J All and Comp, Vol 247 (1997) pp 20-30" />
<Bibitem Id="01Che" Text="Q. Chen and B. Sundman, Modeling of Thermodynamic Properties for BCC, FCC,
Liquid and Amorphous Iron, J Phase Eq, Vol 22 (2001) pp 631-644" />
<Bibitem Id="01Pel" Text="A. D. Pelton, A General Geometric Thermodynamic Model for Multicomponent
solutions, Calphad, Vol 25 (2001) pp 319-328" />
<Bibitem Id="05Lu" Text="X.-G. Lu, M. Selleby B. Sundman, Implementation of a new model for pressure
dependence of condensed phases in Thermo-Calc, Calphad, Vol 29 (2005) pp 49-55" />
<Bibitem Id="07Hal" Text="B. Hallstedt, N. Dupin, M. Hillert, L. Hoglund, H. L. Lukas, J. C. Schuster
and N. Solak, Calphad, Vol 31 (2007) pp 28-37" />
<Bibitem Id="09Sun" Text="B. Sundman, I. Ohnuma, N. Dupin, U. R. Kattner and S. G. Fries, An assessment
of the entire Al-Fe system including D03 ordering, Acta Mater, Vol 57 (2009) pp 2896-2908" />
<Bibitem Id="12Xio" Text="W. Xiong, Q. Chen, P. A. Korzhavyi and M. Selleby, An improved magnetic
model for thermodynamic modeling, Calphad, Vol 39 (2012) pp 11-20" />
<Bibitem Id="13Bec" Text="C. A. Becker, J. Agren, M. Baricco, Q Chen, S. A. Decterov, U. R. Kattner,
J. H. Perepezko, G. R. Pottlacher and M. Selleby, Thermodynamic modelling of liquids:
Calphad approaches and contributions from statistical physics, Phys Stat Sol B (2013) pp 1-20" />
<Bibitem Id="18Dup" Text="N. Dupin, U. R. Kattner, B. Sundman, M. Palumbo and S. G. Fries,
Implementation of an Effective Bond Energy Formalism in the Multicomponent Calphad Approach,
J Res NIST, Vol 123 (2018) 123020" />
<Bibitem Id="20Sun" Text="B. Sundman, U. R. Kattner, M. Hillert, M. Selleby, J. Agren, S. Bigdeli,
Q. Chen, A. Dinsdale, B. Hallstedt, A. Khvan, H. Mao and R. Otis, A method for handling the
extrapolation of solid crystalline phases to temperatures far above their melting point,
Calphad, Vol 68 (2020) 101737" />
</Bibliography>
</Models>