Effect of Aluminum and Vanadium Content Variation on the Thermodynamic Properties of Ti–Al–V Alloys

In this study, the thermodynamic properties and phase transformations of Ti–Al–V alloys were investigated through simulations using the CALPHAD methodology, and the thermodynamic calculations were further validated with experimental data reported in the scientific literature. Phase diagrams and time–temperature–transformation (TTT) diagrams were generated to evaluate the effects of varying Aluminum (5–6–7 wt %) and Vanadium (3–4–5 wt %) contents on the stability and transformation kinetics of the α, β, and Ti3Al phases. To observe changes in both α and β phases, simulations were performed by varying Aluminum (α stabilizer) and Vanadium (β stabilizer) concentrations within critical ranges associated with phase transformations. This approach was designed to enable a comprehensive study that allowed the observation of all variable effects under equilibrium and non-equilibrium conditions. The simulations revealed that increasing Aluminum content enhances the stability of the α phase while leading to earlier precipitation of the Ti3Al phase, which is associated with brittle behavior. When Aluminum content exceeds 6 wt %, the Ti3Al transformation time drops below the maximum aging limit of 24 h for α + β alloys, reaching critical levels. Additionally, increasing Vanadium content was found to improve the stability of the β phase. Below 3.1 wt % Vanadium, the β phase was not thermodynamically stable and did not form in certain temperature ranges, whereas above 3.1 wt %, the β phase formed continuously across all temperatures. This finding established 3.1 wt % as a critical threshold for achieving β phase continuity. These results highlight the importance of identifying critical alloying element ratios to optimize the mechanical and thermal performance of Ti–Al–V alloys. In conclusion, this study provides a comprehensive resource for understanding the effects of alloying elements on the thermodynamic properties of titanium alloys, with phase transformations effectively visualized through detailed graphical representations.