Phase Transition Property Model Settings

The Phase Transition Property Model is available when using the Property Model Calculator in Thermo‑Calc. By varying which condition to relax, it calculates the point when a new phase may form. It is useful to determine melting temperature, boiling temperature or solubility limits. It returns the phase transformation temperature, or composition, depending on the relaxed condition.

For an example, see PM_G_01: Phase Transition.

Configuration Settings

The settings are found on the Property Model Calculator when Phase transition is selected under General Models.

When working in the Configuration window, click the Description tab for more information about the Model.

For the details about the Condition Definitions, Calculation Type, Timeout in minutes, Parallel Calculation, and other calculation associated settings, see Property Model Calculator: Configuration Window Settings.

Choose a Matrix phase, the single phase region to start in. Select Any phase to use the phases that take part of the initial equilibrium or choose a specific phase.

For the new Phase to form, select Any phase or choose a specific phase.

Choose a composition or temperature Condition to vary when calculating the phase transition.

Select the Suspend all other phases checkbox to suspend the phases that are not of interest, which allows for a faster calculation. However, this could mean that metastable equilibria are in fact calculated.

It is best practice to suspend phases on the System Definer by selecting the applicable phases on the Phases and Phase Constitution tab.

For the composition or temperature condition being varied, choose the Search direction to be in a Positive, Negative, or Positive and Negative direction.

The start value is taken from Condition Definitions. The closer the start value is to the actual transition point, the more likely it is that the model will find the transition. Note that the phase transition for a given phase may actually occur in the opposite direction from the selected one.

Plot Renderer Settings

Plot Renderer and Plot Renderer: Configuration Settings

When setting up your calculation on the Plot Renderer and/or Table Renderer, the following axis variables are available for the conditions defined on the Property Model Calculator.

When selecting quantities on the Plot Renderer or Table Renderer, the quantity names include an abbreviated name for the Property Model it is associated to. This is useful in particular when you are calculating two or more Property Models that share names for the quantities. The short name identifying the specific Property Model is included in parentheses after the name of the quantity. Below are the full and abbreviated names for each Property Model.

For a list of the abbreviations associated to a Property Model, see Result Quantities: Property Model Abbreviations.

Select from these plot quantities:

  • Composition
  • Temperature
  • Relaxed condition: Composition (fraction)
  • Relaxed condition: Temperature

Since only one variable can serve as a Relaxed condition per calculation, the quantity that is not relaxed has a NaN result in its corresponding result quantity. The Temperature result quantity inherits the unit set in the conditions while the Composition result quantity inherits the normalization (mole or mass) but always returns a fraction.