mat-calphad-phase-diagram

Goal

To plot macroscopic metallurgical Temperature-composition ($T-x$) binary phase diagrams using the CALPHAD methodology from pre-fitted .tdb thermodynamic databases. This enables the prediction of solidus/liquidus lines, miscibility gaps, and invariant reactions (e.g. eutectics).

Instructions

1. Identify Thermodynamic Database

You must obtain a legitimate .tdb (Thermodynamic Data Base) file for the chemical system of interest.

• You can find databases in published literature or open repositories (like PyCalphad's databases).

2. Plot the Phase Diagram

Use the provided python script to generate the $T-x$ boundary plot.

# Env: calphad-agent
python .agents/skills/mat-calphad-phase-diagram/scripts/plot_phase_diagram.py path/to/database.tdb --elements Element1 Element2 --t-range 300 1000 10 --output research_dir/phase_diagram.png

• --elements: The two chemical symbols to plot. The script computes the binary system.
• --t-range: START STOP STEP in Kelvin. It is recommended to use a step of 10 for reasonable trade-offs between calculation speed and curve smoothness.

3. Verification

Use a visual inspection tool to verify the resulting phase_diagram.png. Ensure that phase labels are clearly visible and there are no overlapping disjoint calculation artifacts (indicative of a database convergence issue).

Examples

Plotting the classic Aluminum-Zinc Phase Diagram (Mey 1993):

# Env: calphad-agent
python .agents/skills/mat-calphad-phase-diagram/scripts/plot_phase_diagram.py .agents/skills/mat-calphad-phase-diagram/examples/Al-Zn/alzn_mey.tdb --elements Al Zn --t-range 300 1000 10 --output Al-Zn_diagram.png

Constraints

• Databases: This skill strictly requires a valid .tdb file.
• Environments: Scripts require the calphad-agent Conda environment because it isolates pycalphad.
• Multicomponent: This specific plotting script focuses on Binary Systems. Ternary isotherms require a separate script not yet implemented.

References

• Richard Otis and Zi-Kui Liu. "pycalphad: CALPHAD-based Computational Thermodynamics in Python." Journal of Open Research Software 5.1 (2017). DOI
• S. Mey, "Re-evaluation of the Al-Zn system", Z. Metallkd. 84(7) (1993) 451-455.

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Author: Bowen Deng Contact: GitHub @learningmatter-mit