Kinetic cross coupling between nonconserved and conserved fields in phase field models.

Area of Science:

• Materials Science
• Computational Materials Science
• Physical Chemistry

Background:

• Phase field models are crucial for simulating materials transformations.
• Understanding kinetic cross-coupling is vital for accurate alloy behavior prediction.
• Macroscopic descriptions often simplify complex microstructural evolution.

Purpose of the Study:

• To develop a phase field model for isothermal transformations in two-component alloys.
• To incorporate Onsager kinetic cross-coupling between phase and concentration fields.
• To reduce the phase field model to a macroscopic free boundary problem.

Main Methods:

• Development of a phase field model including nonconserved and conserved fields.
• Mathematical reduction of the phase field model to a macroscopic free boundary problem.
• Validation through direct phase field simulations and comparison with the reduced model.

Main Results:

• A novel phase field model for two-component alloys with Onsager kinetic cross-coupling is presented.
• The general reduction to a macroscopic free boundary problem is derived.
• Excellent agreement between the reduced model and direct simulations is demonstrated.

Conclusions:

• The developed phase field model accurately captures alloy transformations with cross-coupling effects.
• The reduction to macroscopic descriptions provides a simplified yet valid framework.
• The model and its reduction are relevant for understanding phenomena like solute trapping.