The Spencer Group SpMCBN Database

for 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 containing carbon, nitrogen, boron, and silicon.  The alloys include 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 and Me-B-Si systems.

 

In this updated version of the Database for FactSage 7.3, many new ternary refractory metal  Me1-Me2-Me3 systems have also been included. A list of the newly included and revised systems is as follows:

 

Binary systems:     

    

          C-Ca   Mn-Si

 

Ternary systems:   

 

          B–C–Fe   B–N–Al   B–N–Mn   B–N–Re   B–N–Sc   B–Si-Mn   C–N-Si   C–Si–Mn  

          N–Si–Mn   N–Si–Re   N–Si–Sc   Co-Cr-Re   Cr–Mo–Nb   Cr–Mo–Ni   Cr–Mo–Ta  

          Cr–Mo–Ti   Cr–Mo–V   Cr–Mo–Zr   Cr–Nb–Ta   Cr–Nb–Ti   Cr–Nb–Zr   Cr–Ni–Re  

          Cr–Ni–Ti   Cr–Re–Ta   Cr–Ta–Ti   Cr–Ta–V   Cr–Ta–W   Cr–Ta–Zr   Cr–Ti–Zr 

          Cr–V–W

 

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 2018 Version, calculations of thermodynamic properties and phase diagrams can be carried out for approximately 230 binary, and 367 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 there is a great scarcity of published experimental thermodynamic values for the phases of ternary systems, especially for refractory alloy systems, 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.

 

The elements included in the Spencer Group SpMCBN refractory 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

 

While no data for oxide systems have been included in the database, a number of the elements listed above are important in refractory oxide materials. Reactions of the 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 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 good calculated representation of thermodynamic properties and phase equilibria for the temperatures and temperature ranges covered by the phase diagrams accompanying the documentation of this database.

 

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). Such temperatures exclude use of more common metals because of their lower melting temperatures or oxidation characteristics. Metals such as tungsten, molybdenum, and tantalum are frequently referred to as refractory metals.

While many refractory materials consist of oxides of elements such as silicon, aluminum, magnesium, calcium and zirconium, the SpMCBN Database relates more specifically 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 for particular applications. Some examples of use are in furnace construction, high-temperature coatings, cutting tools, abrasives, aircraft brake linings, rockets, jets, turbines, and nuclear power plants. In steels and light alloys, precipitates of carbides, nitrides and borides give improved properties through added strength, hardness, and grain refining.

 

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 from LIST SpMCBN.