MTDATA – Phase Diagram Software from the National Physical Laboratory







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allows the status of each phase and substance to be altered prior to SAVEing the data for input into one of the calculation modules.







The MISCIBILITY parameter for a phase is normally NONE unless the data are flagged otherwise in the database.


classify absent phase(liq) absent 5,6,7 !

classify absent phase(all) normal phase(diamond,5-7) !

classify miscibility(liquid) 1 miscibility(bcc) 1 !

classify miscibility(bcc) none !

classify normal phase(bcc) ! 

The last two examples have the same effect.

Parameter values:

ABSENT, NORMAL   take the value [phase(p)] [substance(s)] [s]

[ ] = possible omission or repetition. p and s specify phase and number lists, see below

Substances CLASSIFY'd as NORMAL are part of the system and will be written to the current output file when the SAVE command is given; their status will be NORMAL when they are read into the calculation modules. Substances and phases CLASSIFY'd as ABSENT are not written to the output file when the system is SAVEd.

The status EX-SYSTEM of substances is in the parameter menu but substances classified as EX-SYSTEM should never be changed to NORMAL or any other status. Nor should any other status be changed to EX-SYSTEM.

Substances and phases can be specified in the same way:


where the subscript p or s can be any valid number or combination of numbers, "*" or "all" (see examples) obtained from the relevant phase or substance list, given under the list option. Phases and substances may also be identified by any unique abbreviation of the name or formula. Substances may also be specified by quoting the substance number alone.

MISCIBILITY(p) takes the values NONE, 1, 2

The number chosen depends on the number of miscibility gaps expected for the phase, where p is the phase name or number of an individual phase. On saving the relevant phases will be flagged as prone to immiscibility.

General comments:

If a phase is CLASSIFY'd as ABSENT, the corresponding substances as displayed as a result of entering list system substances ! are not flagged as ABSENT, and vice versa. Nevertheless, when the system is SAVEd, these substances are deleted from the SUBSTANCES list, along with the phase. It is very important not to mix data for substances that have the same phase name but employ different models for data representation. Equally substances that in practice do belong to the same phase and do mix in that phase must have exactly the same phase name including any site ratios for sublattice phases.


Updated 24 June 2010