Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session II

MM 20.5: Poster

Dienstag, 2. April 2019, 18:30–20:00, Poster C

Tailoring microstructure of Ni-Mn-Ga single crystals through thermo-magneto-mechanical treatment — •Jonas Heider^1,2, Emmanouel Pagounis², Robert Chulist³, Markus Laufenberg², and Mikhail Fonin¹ — ¹Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany — ²ETO MAGNETIC GmbH, Hardtring 8, 78333 Stockach, Germany — ³Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 30-059 Krakow, Poland

Magnetic shape memory alloys (MSMA) are a promising type of smart material for application in actuators, sensors and energy harvesting devices due to their giant and fast strain induced by a moderate magnetic field or external stress. This strain is based on the motion of twin boundaries of adjoining martensitic twin variants with different orientations. A wide range of materials with varying modulations have been discovered exhibiting magnetic-field-induced strain (MFIS). Among those the Ni-Mn-Ga composition is the most promising MSMA with up to 7.1% MFIS in the five-layered (10M) modulated martensitic phase.

In our work we address the complex microstructure of adjoining twins in Ni-Mn-Ga single crystals in order to understand how different types of twin boundaries can be prepared, preserved and utilized for applications. Crystallographic analysis considering a monoclinic unit cell is performed to identify fine laminates between the macro-twinning planes denoted a/b-laminates. The evolution of the structure and magnetic properties is investigated depending on the thermo-magneto-mechanical treatment of single crystalline samples.