Clear evidence for element partitioning effects in a Ti-6Al-4V alloy by the first-principles phase field method

Area of Science:

• Materials Science
• Computational Materials Science

Background:

• Titanium alloys, specifically Ti-6Al-4V (Ti64), are critical in various engineering applications.
• The mechanical properties of Ti64 are significantly influenced by its alloying components, aluminum (Al) and vanadium (V).
• Understanding element partitioning is crucial for predicting and optimizing alloy performance.

Purpose of the Study:

• To investigate the element partitioning effects of Al and V in Ti64.
• To validate the newly developed first-principles phase field (FPPF) method for analyzing ternary alloys.
• To explore the microstructural transformations of alpha and beta phases by varying Al and V concentrations.

Main Methods:

• Utilized the first-principles phase field (FPPF) method.
• Calculated local free energy using cluster expansion combined with density functional theory.
• Incorporated temperature effects via potential renormalization theory.

Main Results:

• Successfully identified enrichment of Al in the alpha phase and V in the beta phase.
• Provided clear evidence of element partitioning effects for Al and V without empirical thermodynamic parameters.
• Observed microstructural transformations by minor variations in Al and V concentrations.
• Demonstrated excellent agreement between FPPF predictions and experimental results.

Conclusions:

• The FPPF method accurately predicts element partitioning in Ti64.
• The study confirms the significant role of Al and V partitioning in the α + β titanium alloy.
• The FPPF method shows strong potential for analyzing complex alloy systems.