Regensburg 2025 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 21: Interface Controlled Properties, Nanomaterials and Microstructure Design
MM 21.11: Vortrag
Mittwoch, 19. März 2025, 18:15–18:30, H22
Nano-scale precipitations in NiTi-based alloys after laser powder bed fusion: FIB/STEM and APT analyses — •Farzad Khodabakhshi1, Raphael Freundl2, Eric A. Jägle2, and Gerhard Wilde1 — 1University of Muenster — 2Universität der Bundeswehr München
Phase formation and nano-scale precipitation during laser powder bed fusion (LPBF) of a NiTi/Nb powder mixture were characterized throughout the matrix of NiTi using advanced microscopy techniques. The study employed focused ion beam (FIB) preparation combined with scanning transmission electron microscopy (STEM) and atom probe tomography (APT). Different nano-scale phases formed through in situ alloying and their interfacial coherence with the NiTi-based alloy were examined using atomic-scale high-resolution microscopy. Subsequent nano-scale elemental mapping and chemical analysis were performed by APT. The results indicated significant changes in the contributions of in situ formed phases when altering the fraction of niobium. Low fractions of Nb can modify the intrinsic structure of NiTi precipitates. Changing the grain boundary energy helps shift these precipitates toward the interiors of grains rather than remaining at the boundaries. Conversely, increasing the niobium fraction towards the eutectic composition results in the formation of a new structure comprised of precipitates with a specific ternary composition within the NiTi alloy matrix due to LPBF deposition.
Keywords: Precipitation; NiTi alloys; Laser powder bed fusion; Nano-scale characterizations