SpMCBN – Restrictions

The Spencer Group Non-Oxide Refractories Database, SpMCBN, contains assessed thermodynamic parameters for binary and ternary alloys of high-temperature materials. Its use for calculations relevant to higher-order systems is possible, but should take account of the following:

The further growth in the number of assessed systems has necessitated

- the introduction of new elements into existing phases

- the self-compatible combination of phases occurring in different binary and ternary systems for which the thermodynamic modeling used by different authors is not compatible and may represent different ranges of stoichiometry.  

 It is not a realistic proposition to carry out the enormous amount of time-consuming 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.

It is recommended, that when calculating ternary and higher-order phase equilibria, 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 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 color-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.

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.