Point Calculation at Fixed Temperature and Composition

Purpose: Learn to calculate and get detailed phase stability information at a given temperature and composition

Module: PanPhaseDiagram

Thermodynamic Database: AlMgZn.tdb

Batch file: Example_#1.4.pbfx

From the Al-Mg phase diagram shown in Figure 1, we know that two phases, AlMg_Beta+Fcc, are stable at the point indicated by F (the cross of the two dash lines). Other than that, no detail information about this point can be read directly from this phase diagram. In this example, we perform a Point Calculation to obtain the detail information at the selected point.

• Perform 0D calculation following the procedure in Pandat User's Guide: Point Calculation (0D);

• Set Calculation Condition as shown in Figure 2;

Calculation Method 2 from labeling:

• After the Al-Mg phase diagram is calculated, click on the Labeling mode, then put the cursor at the selected point and press Ctrl button, click the mouse.

Information obtained from this calculation:

• Two phases, AlMg_Gamma and Hcp, are stable at the given condition (temperature and composition);

• The G, H, S, and Cp of the system at the given composition and temperature are -22744.9 J/mol, 6539.3 J/mol, 51.0935 J/K·mol, and 30.2876 J/K·mol, respectively;

• The equilibrium composition of AlMg_Gamma is x(Al) = 0.409686, x(Mg) = 0.590314;

• The mole fraction of AlMg_Gamma is 0.687999 (weight fraction is 0.696044);

• The G, H, Cp, G^ex, and H^ex of AlMg_Gamma at equilibrium composition are -23186.3 J/mol, 5976.71 J/mol, 31.3752 J/K·mol, 135.828 J/mol, and 146.6 J/mol, respectively;

• The site fraction of AlMg_Gamma are: =1, =0.0291951, =0.970805, =0.96088, =0.0391201;

• The equilibrium composition of Hcp is x(Al) = 0.058129, x(Mg) = 0.941871;

• The mole fraction of Hcp phase is 0.312001 (weight fraction is 0.303956);

• The G, H, Cp, G^ex, and H^ex of Hcp at equilibrium composition are -21771.6 J/mol, 7779.87 J/mol, 27.8893 J/K·mol, 179.735 J/mol, and 184.813 J/mol, respectively;

• The site fraction of Hcp is the same as its composition since it is essentially one sublattice model, the second sublattice is occupied by vacancy.