mat-calphad-property-diagram

Goal

To predict the equilibrium phase stability, phase fractions, and other extensive thermodynamic properties for a fixed multi-component alloy at different temperatures using PyCalphad. Very useful for modeling solidification, heat treatment paths, and precipitation sequences.

Instructions

1. Identify Thermodynamic Database

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

2. Plot Equilibrium Phase Fractions

Calculate what phases are present, and their molar fractions, across a cooling/heating schedule for a fixed composition.

# Env: calphad-agent
python .agents/skills/mat-calphad-property-diagram/scripts/plot_phase_fractions.py path/to/database.tdb --elements Element1 Element2 --composition Element2 0.3 --t-range 300 1000 10 --output research_dir/phase_fractions.png

• --composition: The solute element and its molar fraction (e.g. Zn 0.3 means 30 mol% Zn).
• --t-range: START STOP STEP in Kelvin. Ensure solving across liquidus and solidus.

Examples

Evaluating phase fractions for an Al-40%Zn alloy as it cools:

# Env: calphad-agent
python .agents/skills/mat-calphad-property-diagram/scripts/plot_phase_fractions.py .agents/skills/mat-calphad-phase-diagram/examples/Al-Zn/alzn_mey.tdb --elements Al Zn --composition Zn 0.4 --t-range 300 900 10 --output phase_fractions.png

Constraints

• Environments: Scripts require the calphad-agent Conda environment.
• Only plots equilibrium step (lever-rule). For non-equilibrium fast solidification (Scheil), custom scripting is required.

References

• Richard Otis and Zi-Kui Liu. "pycalphad: CALPHAD-based Computational Thermodynamics in Python." Journal of Open Research Software (2017).

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Author: Bowen Deng Contact: GitHub @learningmatter-mit