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MM: Fachverband Metall- und Materialphysik

MM 8: Microstructure and Phase Transformations - Processing

MM 8.4: Vortrag

Montag, 16. März 2020, 12:30–12:45, IFW B

Microstructural evolution of Mn₃Ga due to annealing in magnetic field — •Gloria Kirste, Christian G.F. Blum, Jens Freudenberger, Sabine Wurmehl, and Bernd Büchner — Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden, Germany

Due to its D0₂₂ structure Mn₃Ga can be described as a tetragonally distorted binary Heusler compound. The magnetic properties resulting from this crystallographic structure make the material an interesting candidate for application in spin torque devices or as a rare-earth-free permanent magnet. However, the Mn-Ga phase diagram is rather complex such that the D0₂₂ phase cannot be obtained by melting but needs further heat treatment. Moreover, the magnetic characteristics are affected by the material’s microstructure and texture.

Within this study arc melted Mn₃Ga was deformed by rotary swaging to promote the phase transformation. After annealing for up to two weeks the change in microstructure was analysed. The results of X-ray diffraction provide information on the present crystallographic phases whereas microscopical methods revealed the grain size distribution. Some of the resulting magnetic characteristics were examined using SQUID magnetometry.

Several samples experienced annealing in a high static magnetic field as another aid to phase transformation and also in order to achieve a more pronounced texture. The value of magnetic field annealing as a tool for stimulating phase transformation and tuning microstructure will be discussed.