Third-Generation Thermodynamic Descriptions for Ta-Cr and Ta-V Binary Systems.

Area of Science:

• Materials Science
• Thermodynamics
• Alloy Design

Background:

• Refractory high-entropy alloys (RHEAs) are critical for high-temperature applications.
• Accurate thermodynamic databases are essential for designing RHEAs with desired phases, such as Laves phases.
• Existing thermodynamic models for Ta-Cr and Ta-V systems require refinement for advanced alloy development.

Purpose of the Study:

• To establish third-generation thermodynamic descriptions for the Ta-Cr and Ta-V binary systems.
• To construct a reliable thermodynamic database for RHEAs containing Laves phases.
• To improve the predictive capability of phase diagrams and thermodynamic properties for these systems.

Main Methods:

• Utilized the CALPHAD (CALculation of PHAse Diagrams) approach for thermodynamic modeling.
• Established third-generation Gibbs energy expressions for pure Cr and V in solid and liquid phases.
• Evaluated thermodynamic parameters for C14 and C15 Laves phases using theoretical and experimental data.

Main Results:

• Developed reliable thermodynamic descriptions for Ta-Cr and Ta-V systems across all compositions and temperatures.
• Thermodynamic properties and phase diagrams calculated using the new parameters show excellent agreement with experimental data, even at 0 K.
• The models accurately describe thermodynamic properties and thermal vacancy in pure Cr and V.

Conclusions:

• The developed thermodynamic descriptions provide a reliable database for RHEAs containing Laves phases.
• The CALPHAD approach, combined with theoretical and experimental data, successfully models complex phase behaviors.
• This work enhances the understanding and design of advanced refractory alloys for demanding applications.