The effect of vanadium on the microstructure and mechanical properties of TiAl alloy fabricated by twin-wire directed energy deposition-arc

In recent years, additive manufacturing of titanium aluminide has become an attractive research area. In order to improve microstructure and mechanical properties, element additions to additive manufacturing fabricated ti-tanium aluminide have been continuously a concern. In the present research, vanadium has been successfully introduced into gamma-TiAl alloy using twin-wire directed energy deposition-arc (TW-DED-arc) method, which aims to improve strength and plasticity of as-deposited TiAl component. A throughout research on microstructure, chemical composition homogeneity and mechanical properties of TW-DED-arc deposited Ti-48Al and Ti-48Al-2V alloys is investigated. The experiment results show that as-fabricated gamma-TiAl alloys possess layered fully lamellar microstructure consisting of columnar and equiaxed grains. Vanadium exhibits neither positive nor negative segregation during solidification process of TW-DED-arc but partitions to alpha 2 phase in as-deposited Ti-48Al-2 V alloy. As a beta-stabilizing and solid-solution element of gamma-TiAl intermetallic, vanadium additions cause increase of alpha 2 phase content, decrease of lamellar spacing and gamma phase lattice contraction of TW-DED-arc fabricated TiAl alloy. Moreover, introduction of vanadium is capable of enhancing tensile properties under both room tem-perature and high temperature, with -35% improvement in tensile strength and -65% improvement in elongation. Importantly, microstructural effects and strengthening mechanism of vanadium additions are investigated in detail. Generally, the findings provide a valuable reference for alloying element additions to additively manufactured TiAl alloy.

Automated summary

In recent years, there has been increasing interest in additive manufacturing of titanium aluminide. Element additions have been a concern in order to improve the microstructure and mechanical properties of additively manufactured titanium aluminide. This study successfully introduced vanadium into gamma-TiAl alloy using the twin-wire directed energy deposition-arc (TW-DED-arc) method, aiming to enhance the strength and plasticity of the deposited TiAl component. The research investigated the microstructure, chemical composition homogeneity, and mechanical properties of TW-DED-arc deposited Ti-48Al and Ti-48Al-2V alloys, and found that vanadium additions improved the properties of the alloy.