Designing & Printing Dispersion Strengthened Ti-6Al-4V via Laser Powder Bed Fusion Additive Manufacturing

The anisotropy of the mechanical properties of Ti-6Al-4V additively manufactured (AM) via laser powder bed fusion (PBF-LB) is increased by the long and textured columnar prior β grains that typically occur despite the high cooling rates (10 ⁵ -10 ⁷ K/s). Additionally, both AM and conventionally fabricated Ti-6Al-4V exhibit dwell-fatigue sensitivity at room temperature, resulting in premature failure in the low-cycle fatigue regime. This work explores the designing and printing of yttria ( Y ₂ O ₃ ) dispersion hardened Ti-6Al-4V with minimal powder feedstock preparation. A uniformly dispersed bimodal distribution of Y ₂ O ₃ with mean particle sizes of ∼ 404 nm and 174 nm in the Ti-6Al-4V matrix decreases the transverse size of the prior β grains. Furthermore, STEM bright field micrographs reveal dispersoid pinning of dislocations and STEM EDS confirms that the dispersoids are Y ₂ O ₃ as expected. A modest increase in room temperature microhardness is observed and room temperature nanoindentation creep results show a ∼ 64% lower mean creep rate compared to standard PBF-LB Ti-6Al-4V. This work successfully demonstrates the use of PBF-LB to fabricate oxide dispersion strengthened (ODS) Ti-6Al-4V with minimal feedstock preparation enabling refinement of the prior β grain and improved localized mechanical properties.