Towards Suppressed Microstructural Anisotropy and Superior Mechanical Properties in Additively Manufactured Ti5553 Alloy Through Ta Doping

Abstract

Laser powder bed fusion (L-PBF) of near-β titanium alloys typically produces coarse columnar grains and strong <001> textures, which induce anisotropic mechanical behavior. Here, 5 wt.% tantalum (Ta) particles were doped into Ti-5Al-5Mo-5V-3Cr (Ti-5553) powder to concurrently inhibit microstructural anisotropy and contribute to enhanced strength–ductility synergy via solidification modification. During the L-PBF process, unmelted Ta particles provided heterogeneous nucleation sites, while dissolved Ta generated local constitutional undercooling. Together, these effects reduced the average β-grain size from 47.23 ± 27.5 to 12.28 ± 11.8 μm and weakened the <001> texture, as well as increased yield strength from 870 to 990 MPa while retaining 28% elongation. After solution treatment and aging, Ti-5553-Ta reached a yield strength of 1196 MPa and 16.0% elongation. Local Ta-enriched precipitate-free zones and refined α precipitates contributed to the improved post-treatment ductility.