Simultaneously improved strength and ductility of low-cost Ti-Al-V-Fe alloy with TiB2 addition and thermomechanical processing

Abstract

To obtain the low-cost titanium alloys with simultaneously improved strength and ductility by thermomechanical processing, 0.1 wt% of boron was added to the Ti-4Al-2.5V-1.5Fe alloy using titanium diboride (TiB2) as a boron source. The deformation mechanisms and microstructure evolution were systematically studied by comparative investigation of Ti-4Al-2.5V-1.5Fe alloys with and without boron. The results indicated that the addition of boride had a significant effect on the material parameters. Furthermore, TiB greatly improved the spheroidization and recrystallization of the alloy, and it can effectively limit grain growth during thermal exposure. Consequently, both high-temperature forging and further thermal deformation facilitated the generation and retention of the fine grain structure, dramatically improving the processibility of Ti alloys. For bare alloys, severe plastic deformation often leads to inhomogeneous microstructures and flow instability, which is harmful to mechanical integrity. In contrast, the addition of borides can significantly mitigate flow localization. In this study, boron-modified titanium alloys exhibited improved processibility and beneficial mechanical properties attributed to beneficial effects due to the addition of borides, which may enable new strategies for manufacturing high-strength titanium alloys in a more cost-effective way.