Phase Fraction as a Function of Composition

Purpose: Learn to calculate and use a phase fractions vs. composition plot

Module: PanPhaseDiagram

Thermodynamic Database: AlMgZn.tdb

Batch file: Example_#1.2.pbfx

Figure 1 is the Al-Mg binary phase diagram, which clearly shows the single phase region, two-phase region, three-phase equilibrium. However if you want to know the fraction of a stable phase in a two-phase field at a certain temperature, you need to draw a horizontal line at this temperature and calculate it by line (1D) calculation. In this example, we calculate the fraction of each phase as a function of composition, x(Mg), at 300°C (the red dash line).

Calculation Procedures:

• Load AlMgZn.tdb following the procedure in Pandat User's Guide: Load Database, and select Al and Mg two components;

• Perform 1D calculation following the procedure in Pandat User's Guide: Line Calculation (1D);

• Set Calculation Condition as shown in Figure 2;

Post Calculation Operation:

• Add legend for graph following the procedure in Pandat User's Guide: Icons for Graph on Toolbar;

• Change graph appearance following the procedure in Pandat User's Guide: Property;

Information obtained from this calculation:

• The composition range that a phase is stable at the selected temperature;

• In a single phase field, the fraction of the stable phase is 1;

• In a two-phase field, the fraction of one phase decrease from 1 to 0, while the other increase from 0 to 1 as shown in Figure 3

• Details on the fraction of each phase as a function of composition can also be found in the Default table as shown in Figure 4;