The Development of Ultrafine Grain Structure in an Additively Manufactured Titanium Alloy Via High-Temperature Microscopy

• DOI: 10.2139/ssrn.4462022
• Publication Date: 2023-05-31T19:37:09Z
• Authors: Marco Simonelli; Zhiyi Zou; Pere Barriobero-Vila; Yau Yau Tse
• Keywords: Titanium alloy; Equiaxed crystals; Titanium aluminide; Ductility (Earth science)

Microstructures dominated by acicular α' martensitic phase, such as in the case of Ti-6Al-4V fabricated laser powder-bed fusion (PBF-LB), are known to suffer from reduced ductility and low toughness. The decomposition metastable microstructures into α+β lamellar structures during PBF-LB requires either specific regimes that often challenging be attained or post-process heat treatments which might lead, instead, undesirable coarsening grain structure. Here we propose a novel route for formation ultrafine demonstrate associated advantages terms tensile strength ductility. Our approach is based on suitable modification constitution with additions Fe, potent β stabiliser high intrinsic diffusivity. After printing, this alloy presents microstructure phase. We investigate details its using combination in-situ high-energy synchrotron X-ray diffraction temperature microscopy up transus temperature. evolution comprised homogeneous phase via ω-assisted nucleation α growth sustained early diffusion Fe followed conventional partitioning V. understanding transformation pathway enables development grained exhibit outstanding behaviour. presented machine-agnostic offers design strategy high-strength alloys additive manufacturing.