SKM 2023 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 23: Poster II
MM 23.5: Poster
Dienstag, 28. März 2023, 18:15–20:00, P2/OG1+2
The role of electrons during the martensitic phase transformation in NiTi-based shape memory alloys — •Alexander Kunzmann1, Jan Frenzel2, Ulrike Wolff3, Jeong Woo Han4, Lars Giebeler3, David Piorunek2, Martin Mittendorf4, Juliane Scheiter3, Heiko Reith3, Nicolas Perez3, Kornelius Nielsch3,5, Gunther Eggeler2, and Gabi Schierning1 — 1Bielefeld University — 2Ruhr University Bochum — 3IFW-Dresden — 4University of Duisburg-Essen — 5TU Dresden
The present work provides an experimental contribution to the investigation of the role of conduction electrons in the martensitic phase transition of Nickel-Titanium. This material, which is structurally very well studied due to its shape memory effect, still offers room for further knowledge more than 60 years after its discovery. For this purpose, a series of alloys within the equiatomic NiTi phase was characterized by temperature-resolved transport experiments, thermodynamic characterizations and structural investigations. In addition to the well-known resistivity anomaly, a reduction of the charge carrier density by 90% was measured, which has not been described before for this class of materials. Using a novel approach for structural materials, conclusions could be drawn about the entropy of the electronic system and a correlation with the phase transition temperature could be demonstrated. The obtained data allow an interpretation as the formation of a charge carrier density wave phase, which explains both the drastic reduction of charge carriers and the large electronic entropy contribution.