SKM 2021 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 9: INNOMAG e.V. Diploma/Master Prize (2021)

MA 9.3: Vortrag

Mittwoch, 29. September 2021, 13:10–13:30, H2

Optimizing the magnetocaloric effect in all-d-metal Ni-Co-Mn-Ti Heusler alloys — •Benedikt Beckmann and Oliver Gutfleisch — TU Darmstadt, 64287 Darmstadt, Germany

Magnetocaloric refrigeration is a promising cooling technology which could be an environmentally friendly and more energy efficient alternative to conventional vapor compression refrigeration. Among magnetocaloric materials, Ni-Mn based Heusler alloys, showing a first-order magnetostructural phase transition, are promising candidates. In this study, a systematic analysis of all-d-metal Ni50-xCoxMn50-yTiy Heusler alloys is carried out [1]. Due to their enhanced mechanical stability, these alloys can also be utilized in cooling cycles that apply magnetic field and pressure as external stimuli to induce the phase transition. A systematic heat treatment optimization is carried out, resulting in a substantial decrease of the transition width down to only 4 K. The microstructural differences between as-cast and differently annealed alloys are analyzed in detail by in-situ polarized light microscopy. As a result, large isothermal entropy changes up to
38 Jkg^-1K^-1 are achieved in 2 T. The adiabatic temperature change is measured directly for this material system and values up to -3.8 K for the first field application and -0.8 K under cyclic conditions are obtained in moderate magnetic field changes of 1.93 T.

We acknowledge financial support from DFG (CRC/TRR 270) and ERC (Adv. Grant No. 743116).

[1] A. Taubel & B. Beckmann et al., Acta Materialia 201, 425-434 (2021)