|About this Abstract
|2023 TMS Annual Meeting & Exhibition
|Additive Manufacturing and Innovative Powder/Wire Processing of Multifunctional Materials
|Improving Tensile Strengths of Laser-Direct Energy Deposited (L-DED) NiTiHf Alloys by Printing Dislocation Structures
|Soumya Mohan, Aaron Stebner
|On-Site Speaker (Planned)
Additive manufacturing of NiTi shape memory alloys for biomedical applications requiring superelasticity is challenging due to the poor tensile performance of as-printed parts. Improving tensile strength by traditional approaches like aging heat treatments and cold work to add precipitation strengthening and dislocation strengthening respectively, are difficult to adapt to the complex geometries of AM NiTi parts. We attempted to improve tensile strengths of AM NiTi alloys by introducing a ternary alloying element, that would actively segregate during AM solidification, and help print dislocation structures into the as-solidified microstructure. Candidate ternary alloying elements were explored through non-equilibrium Scheil simulations, and Hf was selected for printing NiTiHf alloys. Hf segregation was indeed observed at the solidification cell boundaries in the as-printed microstructure for several samples printed using Laser Direct Energy Deposition process with varying power and scan speeds. Transmission electron microscopy will be used to confirm the presence of such dislocation structures.
|Additive Manufacturing, Solidification, Other