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Calculation of phase boundary temperatures in multicomponent, multiphase systems for a fixed composition and pressure

Typically this application might be used for calculating the phase boundaries encountered on cooling down a melt. After having loaded the appropriate data into MTDATA and selected the phase classifications as required, this application is initiated by entering "transn_t.mac". Prompts are provided to help the user to decide what to type in next.

The first prompt asks for the maximum number of phase boundaries to be found. In order to find them all a relatively high number eg 20 should be entered.

The next prompt asks for the identify any phase expected to be present alone at high temperatures. If it is not important for this to be checked a value of 0 can be given.

Before it is possible to do a calculation, it is necessary to set the composition required (using the set command) and the range of temperatures required for the calculations (using the range command). The RANGE command here requires three values. The first two values indicate respectively the minimum and the maximum temperatures for the calculations. The third value is a tolerance in temperature and is an indication of how precisely the calculations should be carried out. A tolerance of 0.1 degree should result in values calculated to a fairly high degree of precision.

The computer output (following the entry of "compute !") for this application consists of:

The composition set both in terms of moles and masses of the components
The maximum number of phase boundaries to be searched for
The maximum temperature for the calculations
The set of phases stable in the particular temperature range
The temperature of any phase boundaries encountered
The minimum temperature for the calculations

The output might look something like this:

Component moles and masses
  12.53424527468071      0.7000000000000000
   3.846449718683123     0.2000000000000000
   0.7296226708878857    7.0000000000000000E 02
   2.497710441412475     2.9999999999999999E 02
Number of phase boundaries requested 20

Maximum temperature     2500.00
Boundary temperature    1529.11
Boundary temperature    1515.29
LIQUID      FCC_A1      M7C3
Boundary temperature    1463.76
LIQUID      FCC_A1      M7C3       M6C
Boundary temperature    1462.74
FCC_A1      M7C3        M6C
Boundary temperature    1412.91
FCC_A1      M7C3        M23C6      M6C
Boundary temperature    1392.51
FCC_A1      M7C3        M23C6
Boundary temperature    1378.39
FCC_A1      M23C6
Boundary temperature    1066.36
BCC_A2      FCC_A1      M23C6
Boundary temperature    1064.62
BCC_A2      FCC_A1      M7C3       M23C6
Boundary temperature    1063.62
BCC_A2      M7C3        M23C6
Boundary temperature     764.24
BCC_A2      M3C2        M7C3       M23C6
Boundary temperature     749.62
BCC_A2      M3C2        M23C6
Maximum temperature      500.00


Updated 7 May 2010