Making a T0 Temperature Simulation

This describes how to perform a T0 temperature simulation and apply a stepping calculation to its initial result.

Before you perform a T0 temperature calculation, you must have defined your initial system and be in POLY. The initial overall composition must have appropriate settings for the desired T0 temperature calculation for the two target phases.

POLY Module Commands

  1. Use SET_CONDITION to set the conditions of your calculation in the same way as when you calculate an ordinary equilibrium.
  2. Use COMPUTE_EQUILIBRIUM to run the calculation. The calculation does not need to reach an equilibrium in which any of the target phases is stable.
  3. When you have calculated your initial equilibrium, use ADVANCED_OPTIONS and choose T-zero.
  4. When prompted, specify the names of the two target phases for which the T0 temperature (where the phases’ Gibbs energies are equal) is to be calculated.
  5. If the T0 temperature between the two target phases is calculated, this temperature (in Kelvin) is shown in the Console window. 
  6. If you want to do a stepping calculation based on this initial T0 temperature calculation, then use SET_AXIS_VARIABLE to specify which state variable to use as the stepping variable. This is done the same way as when you calculate a normal property diagram.

When a T0 temperature simulation is run, you cannot set temperature as the stepping variable.

  1. Use STEP_WITH_OPTIONS and choose T-zero to initiate the stepping calculation. You are prompted to specify the names of the target phases for which the T0 temperature is calculated.

During the STEP T-ZERO calculation procedure, the calculated T0 values are presented next to the stepping variable.

For example, part of the output might look like this:

Phase Region from   1.000000E-01 for:

BCC_A2

FCC_A1

1.000000E-01         940.24

9.250000E-02         941.20

2.500000E-03         977.61

7.500000E-09         979.34

When the stepping calculation has finished, you can move to the POST module and plot the T0 line against the stepping composition variable or another varying axis value. Or you can impose the calculated T0 line onto a normal phase diagram.