Effects of V Element and Heat Treatment Process on Microstructure and Mechanical Properties of Additive Manufacturing of Titanium Aluminum Alloy Using Flux-Core Arc Welding Wire with TiH₂ Powder

A TiH₂ powder-cored wire-based additive manufacturing method utilizing tungsten inert gas is used to fabricate TiAl alloy. The interdependent effects of vanadium elements and heat treatment on microstructure, phase composition, and mechanical properties are examined. The TiAl alloy exhibits a banded microstructure, alternating between the diplex structure and full lamellar regions. Introducing vanadium elements results in a microstructure dominated by the full lamellar region, while subsequent heat treatment processes reduce lamellar thickness. The stable region displays cellular γ and γ lamellar structures, with a 2.3% α₂ phase volume fraction. In normal temperature conditions, the alloy has a tensile strength of 243 MPa and an elongation of 0.34%. Incorporating vanadium elements leads to a full lamellar structure, increasing the α₂ phase volume fraction to 14%. This modification results in a notable enhancement of tensile strength to 309 MPa and an elongation of 0.4%. Heat treatment processes refine the lamellar structure, leading to a higher α₂ phase volume fraction of 65%. Consequently, this significantly improves tensile strength, reaching 416 MPa while increasing elongation to 0.47%. The combined effect of V addition and heat treatment effectively enhanced the TiAl alloy’s strength and ductility.