The Spencer Group SpMCBN Database

for

Refractory Alloy-Carbide, -Nitride, -Boride and -Silicide Systems

 

General

 

The Spencer Group Non-Oxide Refractories Database, SpMCBN, contains assessed thermodynamic parameters for binary and ternary alloys of high-temperature materials. These materials are frequently based on transition metal alloys and on their carbides, nitrides, borides, and silicides. 

 

The alloys comprise Me1-Me2-C, Me1-Me2-N, Me1-Me2-B, Me1-Me2-Si, Me-C-N,

Me-C-B, Me-C-Si, Me-N-B, Me-N-Si, Me-B-Si and Me1-Me2-Me3 systems.

 

The elements included in the Database are:

 

B,  C,  N,  Si  with

 

Al,  Ca,  Co,  Cr,  Fe,  Hf,  Mg,  Mn,  Mo,  Nb,  Ni,  Re,  Sc,  Ta,  Tc,  Ti,  V,  W,  Y,  Zr

 

In this updated version of the Database for FactSage 8.1, a further large number of assessed binary (12) and ternary (125) refractory metal Me1-Me2-Me3 systems have been included.

 

The further growth in the number of assessed systems has necessitated the introduction of new elements into existing phases, as well as the self-compatible combination of phases occurring in different binary and ternary systems, but for which the thermodynamic modeling used by different authors is not compatible and often represents differing ranges of stoichiometry.  

 

It is not a realistic proposition to carry out the massive and time-consuming amount of work required to produce self-compatible re-assessments of those systems for which there is incompatibility in the published modeling. For this reason, development of the present database has been achieved, in some cases, by simplification of certain phases, such as the MU and LAVES phases, which often display limited ranges of stoichiometry, to line compounds. This allows calculations for higher-order systems which are still of satisfactory reliability with respect both to thermodynamic properties and phase equilibria.

 

The simplified modeling used for certain frequently occurring phases observed in refractory alloy systems is exemplified here for the MU phase.

 

The MU-Phase description in the SpMCBN Database is based on a 3-sublattice model with site occupation 7:2:4. The element occupation of the lattices is

 

7:    Co,  Cr,  Fe,  Mn,  Mo,  Nb,  Ni,  Ta,  V

2:    Mn,  Mo,  Nb,  Ta,  Ti,  V,  W,  Zr

4:    Co,  Cr,  Fe,  Mn,  Mo,  Nb,  Ni,  Ta,  Ti,  V,  W,  Zr

 

Because the MU-Phase has the general stoichiometry of M7X6 (where M and X are the two elements involved) the model does not allow representation of those systems in which Co, Fe, and Ni correspond to X6 in the formula  (e.g. Ta7Ni6, Nb7Ni6, Nb7Co6, etc.), because Co, Fe and Ni are not present on the sublattice with occupation 2.

For this reason, the M7C6 phase has been created with stoichiometry M7X6 or X7M6, as a simplification allowing the MU-Phase to be treated as a line compound as and where necessary.

 

This simplified stoichiometric format, used for phases displaying small ranges of composition allows mixing descriptions in higher-order systems not only for the MU-Phase, but also for other non-stoichiometric phases which appear frequently in refractory metal alloys. Examples of the effect of some simplifications on calculated binary phase equilibria are illustrated in the following diagrams.

 

 

Because these simplifications have relevance for many ternary systems, it has been necessary to rename several phases. This has resulted in revised phase diagram figures in the FactSage Documentation.

 

Calculations for binary systems are generally not affected by this issue, but when calculating ternary (and higher-order) phase equilibria, it is recommended that the user retain the pre-selected phases used in producing the calculated phase diagrams for the  SpMCBN Database shown in the Documentation.  All phases relevant for a system of interest can be viewed by selecting ‘File’ in the top left-hand corner of the components page of the Phase Diagram module, then ‘Directories’ and then ‘SpMCBN phase diagrams.’  This will generate a list of all phase diagrams in the SpMCBN Database and choice of a particular system(s) from the list will reveal which compound and solution phase selections were made from the available choices to produce the illustrated phase diagram(s). 

  

The following stoichiometries and the corresponding phase names represent simplifications used frequently in ternary phase diagram calculations.

 

Phase Stoichiometry                         Phase Name(s)

 

A7B2                                                      C7NT

A3B                                                        CFN3

A2B                                                        CFN2

A7B6                                                      M7C6

AB                                                          CFNT

AB2                                                        CNT2

 

A list of the newly included and revised systems is as follows:

 

Binary: 

 

Co-Mo (simplified),   Co-Nb (simplified),   Co-Ta (simplified),  

Co-Ti (simplified),   Co-W (simplified),   Fe-Mo (simplified),

Fe-Nb (simplified),   Fe-W (simplified),   Fe-Zr (simplified),

Mo-Ni (simplified),   Nb-Ni (simplified),   Ni-Ta,   Ni-Ta (simplified)

 

Ternary:

 

Co-Cr-Mo,    Co-Cr-Ta,   Co-Cr-W,   Co-Fe-Mo,   Co-Fe-Nb,   Co-Fe-W,   Co-Mo-Ni,                                    

Co-Mo-Si,   Co-Mo-Nb,   Co-Mo-Ta,   Co-Mo-Ti,   Co-Mo-W,   Co-Mo-Zr,  

Co-Nb-Ni,   Co-Nb-Si,   Co-Nb-Ta,   Co-Nb-Ti,   Co-Nb-W,   Co-Nb-Zr,   Co-Ni-Ta,   Co-Ni-W,   Co-Si-W,   Co-Ta-W  

 

Cr-Fe-Mo,   Cr-Fe-Nb,   Cr-Fe-W,   Cr-Mn-Ti,   Cr-Mo-Ni,   Cr-Mo-V,   Cr-Nb-Ni,    Cr-Nb-Ta,   Cr-Nb-Zr,   Cr-Ni-Ta,   Cr-Ni-V,   Cr-Ni-Zr,   Cr-Ti-V,   Cr-Ti-Zr

 

Fe-Mo-Nb,   Fe-Mo-Ni,   Fe-Mo-Ta,   Fe-Mo-Ti,   Fe-Mo-V,   Fe-Mo-W,   Fe-Mo-Y,

Fe-Mo-Zr,   Fe-Nb-Ni,   Fe-Nb-Ta,   Fe-Nb-Ti,   Fe-Nb-W,   Fe-Nb-Y,   Fe-Ni-Re,

Fe-Ni-Ta,   Fe-Ni-W,   Fe-Ni-Y,   Fe-Ta-W,   Fe-Ta-Y,   Fe-Ti-W,   Fe-W-Y

 

Hf-Mo-Re,   Hf-Nb-V,  

Mn-Mo-Ni,   Mn-Ni-W  

 

Mo-Nb-Ni,   Mo-Nb-Re,   Mo-Nb-Ta,   Mo-Nb-Ti,   Mo-Nb-W,   Mo-Nb-Zr,   Mo-Ni-Re,    Mo-Ni-Si,   Mo-Ni-Ta,   Mo-Ni-Ti,   Mo-Ni-V,   Mo-Ni-W,   Mo-Ni-Zr,   Mo-Ta-Ti,

Mo-Ta-V,   Mo-Ti-V,   Mo-Ti-Zr,   Mo-V-W,   Mo-V-Zr,   Mo-W-Zr,   Mo-Y-Zr

 

Nb-Ni-Re,   Nb-Ni-Si,   Nb-Ni-Ta,   Nb-Ni-Ti,   Nb-Ni-W,   Nb-Ni-Zr,   Nb-Re-Ta,       Nb-Re-V,   Nb-Re-W,   Nb-Re-Zr,   Nb-Ta-Ti,   Nb-Ta-V,   Nb-Ta-W,   Nb-Ta-Zr,      Nb-Ti-V,   Nb-Ti-W,   Nb-Ti-Zr,   Nb-V-Zr,   Nb-W-Zr

 

Ni-Re-Ta,   Ni-Re-Ti,   Ni-Re-V,   Ni-Re-Zr,   Ni-Ta-Ti,   Ni-Ti-V,   Ni-Ti-W,   Ni-Ti-Y,   Ni-Ti-Zr,   Ni-W-Zr

 

Re-Ta-V,   Re-Ta-Zr,    Re-V-W,   Re-V-Zr

 

Ta-Ti-V,   Ta-Ti-W,   Ta-Ti-Zr,   Ta-V-W,   Ta-V-Zr,   Ta-W-Zr

 

Ti-V-W,   Ti-V-Zr,   Ti-W-Zr

 

A further development of the SpMCBN Database in FactSage 8.1 is represented by the introduction of volumetric and thermal conductivity parameters for 184 pure solid phases. Volumetric properties (density at 298.15K, volumetric thermal expansivity, compressibility and derivative of the Bulk Modulus) and thermal conductivity parameters (based on the Debye Temperature, Gruneisen Parameter, and atoms per crystallographic cell) are now available for the following carbides, nitrides and borides:

 

Carbides

 

AlTi2C

AlTi3C

Co3AlC

Cr2AlC

Cr23C6

Cr7C3

Cr3C2

Fe3AlC

Hf3Al3C5

Hf5Al3C

Hf2Al3C4

Mn5C2

Mn7C3

Mn23C6

MoC

Mo3Al2C

Mo3Ni3C

Mo6Ni6C

Nb2AlC

Nb4Co2C

Nb4Ni2C

Sc3C4

Sc4C3

Ta2AlC

Ta5Al3C

Ta4Co2C

V2AlC

WC

Zr3Al3C5

Zr5Al3C

 

Nitrides

 

h-AlN

h-BN

Co4N

Co2V4N

Hf3AlN

Hf5Al3N

Hf2N

Hf3N2

Hf4N3

Mn4N

Mn6N4

MnSiN2

Nb3Al2N

Nb4Co2N

Nb3Fe3N

Nb4Ni2N

Ni2V4N

ScN

Si3N4

TaMoN

TaN_S1

Ta4Ni2N

Ti2AlN

Ti3AlN

Ti2N

WN_S1

YN

Zr3AlN

Zr5Al3N

 

 

Borides

 

AlB2

CaB6

CoB

Co2B

Co3B

CrB

CrB2

Cr3B4

Cr2B

CrB4

FeB

Fe2B

FeB2

HfB2

MgB2

MgB4

MgB7

MnB

MnB2

MnB4

Mn2B

Mn3B4

MoB

MoB2

MoB4

Mo2B

Mo3B2

NbB

NbB2

Nb3B2

Nb3B4

NiB

Ni2B

Ni3B

Ni4B3

ReB2

Re3B

Re7B3

ScB2

ScB12

TaB

TaB2

Ta2B

Ta3B2

Ta3B4

TcB2

Tc3B

Tc7B3

TiB

TiB2

Ti2B

Ti3B4

VB

VB2

V2B3

V3B2

V3B4

W2B

WB4

YB2

YB4

YB6

YB12

ZrB

ZrB2

ZrB12

 

 

 

 

AlCr2B2

AlCr3B4

AlFe2B2

Co21Cr2B6

Co21Hf2B6

Co20V3B6

CoVB3

Cr5B3

CrSc2B6

HfCo3B2

Hf9Mo4B

Hf2Ni21B6

MoAlB

MoCoB

Mo2CoB2

Mo2Co21B6

Mo2NiB2

Mo5SiB2

MoTiB2

MoYB4

Nb2Co21B6

Nb3Co4B7

Nb3Co5B2

NbFeB

Ni20All3B6

NiCr3B6

Ni3Cr2B6

NiScB4

Ni21Sc2B6

Ni6Si2B

Re3Al2B

ReCoB

Re5Co2B4

ReTi2B2

ReYB4

ReY2B6

ReY3B7

Re4YB4

Ta2Co21B6

Ta3Co5B2

Ta2Ni21B6

WCoB

W2CoB2

W2Co21B6

W2FeB2

W3Hf9B2

W2NiB2

WY3B7

YCoB4

YCo2B2

YCo3B2

YCo4B

YCo12B6

YCrB4

Y5Si2B8

Zr2Co21B6

Zr2Ni21B6

 

 

 

 

 

The database is based on, and is compatible with, assessed data for relevant binary, and some ternary systems from the SGTE2014 Solution Database, but the SpMCBN Database incorporates thermodynamic parameters for very many previously un-assessed systems. In its updated 2021 Version, calculations of thermodynamic properties and phase diagrams can be carried out for ca. 250 binary, and 560 ternary systems, for the individual temperatures or temperature ranges covered by the available experimental information.

 

The general procedure used in obtaining assessed parameters for the solution and compound phases of the large number of previously un-assessed ternary systems in the SpMCBN Database has been to combine the phase boundary information contained in the ASM Handbook of Ternary Alloy Phase Diagrams, 1995, and in the more recent ASM Alloy Phase Diagram Database, 2016, with available assessed thermodynamic data for the appropriate binary sub-systems. This has allowed a completely compatible set of values to be derived to describe binary and ternary thermodynamic properties and phase equilibria for a particular system. Because the ASM compilations often present, for a given binary or ternary system, several published phase diagrams which differ from each other, those authors of the diagram to which greatest weight has been given in the present assessment work, are listed in the references accompanying the database. 

 

There is a great scarcity of published experimental thermodynamic values for the phases of ternary systems, especially for refractory alloys. For this reason, the simplification of additivity of element entropy and heat capacity data has been used frequently as the basis for obtaining a complete set of thermodynamic values for ternary compounds. Enthalpies of formation and standard entropies of the compounds have then been derived to give consistency with the published phase equilibria.

 

While no data for oxide systems have been included in the database, several of the elements

listed above are important in refractory oxide materials. Reactions of the alloy, carbide, nitride, boride and silicide systems with such refractory oxides and with oxygen-containing gas atmospheres can be calculated using FactSage by selecting the SpMCBN database together with appropriate combinations of the FToxid, FACTPS and SGPS databases for the materials in question.

 

The significant experimental difficulties associated with the determination of phase equilibria and thermodynamic properties of materials at high temperatures result in a generally lower accuracy of the assessed thermodynamic parameters for refractory systems. Many of the published experimental ternary phase diagrams originate from work carried out some 30 or more years ago, and in some cases now show incompatibility with accepted binary phase equilibria. However, the data in the SpMCBN database are believed to allow generally reliable calculation of thermodynamic properties and phase equilibria for the temperatures and temperature ranges covered by the phase diagrams accompanying the documentation of this database.

 

The reliability of the assessment for an individual binary or ternary system is summarized under “assessments” in the documentation for the SpMCBN Database. All the assessed systems are presented with colour-coding for the quality of the assessment, in tables headed 

 

SpMCBN Binary Assessments

Ternary Systems with Boron

Ternary Systems with Carbon

Ternary Systems with Nitrogen

Ternary Systems with Silicon

Ternary Alloy Systems without B, C, N or Si.

 

The term “refractory” applied to materials with applications in high-temperature structures or equipment is somewhat indefinite, but generally implies a use above about 1000°C (1273K).

The major applications of the SpMCBN Database relate to the ever-expanding field of non-oxide refractories based on carbides, nitrides, borides and silicides. These are finding wide use, in combination with appropriate elements, to produce hard, high melting temperature materials. Some examples of use are in furnace construction, high-temperature coatings, cutting tools, abrasives, aircraft brake linings, rockets, jets, turbines, and nuclear power plants.

Specific information on the phases present in each alloy system and references to the individual unary, binary and ternary systems in the database can be obtained by consulting the documentation for the SpMCBN Database.

 

N.B. The SpMCBN Database includes many of the elements which are important in steels. It is emphasized, however, that for calculations related to the production and heat-treatment of steels, the FSstel Database should be selected. The assessed data contained in FSstel are based on the much greater amount of accurate experimental data available specifically for steel compositions, than are available for refractory Fe-containing alloys.   

 

Further information on the development and application of the SpMCBN Database can be found in the following two references:

 

P.J. Spencer, Development of a thermodynamic database for refractory boride, carbide, nitride and silicide systems, Proceedings Materials Science and Technology 2017 (MS&T17), 1230-1238.

 

S. Saxena, P. Spencer, V. Drozd, An alternative, environmentally-friendly production process for refractory metal carbides and syngas using methane reduction of the oxide ores, Monatshefte für Chemie in memoriam Heinz Gamsjäger, 149 (2018) 411-422.