MTDATA – Phase Diagram Software from the National Physical Laboratory







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allows the status of each phase and substance to be defined for the purposes of a subsequent calculation. Miscibility gaps in phases may also be specified. 






normal = <all substances, all phases for which a full set of data is available>

misc = as flagged in the datafile or database


classify absent phase(bcc_a2) 1 2 3 normal substance(1) !

classify misc(5) 1 !

classify absent p(*) normal p(1) p(liquid) !

classify absent p(1,2,5-10) !

Parameter values:

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

[ ] = possible omission or repetition

Something CLASSIFY'd as NORMAL is part of the system, whilst something ABSENT is temporarily excluded until restored. 

Substances and phases can all be specified in the same way. * is any valid number obtained from the relevant list, given under the LIST command or * itself. If * is used it refers to all the items in the relevant list.

Substances may also be specified in two other ways:
(a) by quoting the substance number alone.
(b) by giving the substance name, together with its correct phase label, enclosed in quotes; the correct substance name and phase label can be obtained from the relevant list given under the LIST command. This method of specifying the substance is available only if the components are elements.

MISCIBILITY(*) takes the values <number>/NONE

* = <phase number or phase name>

<number> is the number of miscibility gaps to which the specified phase may possibly give rise. It must be less than or equal to 2. The discovery of miscibility gaps cannot be guaranteed. Miscibility gaps should not be classified for pure substance phases.

NONE is equivalent to setting <number> = 0

General comments:

The ABSENT/NORMAL classification is in effect a toggle that ignores, or includes phases, components and substances when the calculation is performed. It can be used as many times as is desired on the same entity within the same session. In the context of the TERNARY module the ABSENT classification provides a facility for examining metastable phases.


Updated 2 July 2010