SKM 2021 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Posters Magnetism IV
MA 15.18: Poster
Donnerstag, 30. September 2021, 13:30–16:30, P
Microstructural aspects of multicaloric cooling using magnetic fields and unaxial stress in Ni-Mn-In Heusler compounds — •Lukas Pfeuffer1, Adrìa Gràcia-Condal2, Tino Gottschall3, David Koch1, Enrico Bruder1, Jonas Lemke1, Andreas Taubel1, Franziska Scheibel1, Konstantin Skokov2, Lluís Mañosa2, Antoni Planes1, and Oliver Gutfleisch1 — 1Technical University of Darmstadt, 64287 Darmstadt, Germany — 2Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain — 3Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
Ni-Mn-based Heusler compounds exhibit giant magneto- and elastocaloric effects, but suffer from irreversibilities during cyclic operation due to their large thermal hysteresis. A promising way to improve cyclic performance is the sequential combination of magnetic field and uniaxial stress in an "exploiting-hysteresis cycle" which utilizes thermal hysteresis rather than avoiding it.
We have studied the influence of microstructure on the caloric response to magnetic fields, uniaxial stress and their combination in an exploiting-hysteresis cycle for Ni-Mn-In. By correlating XRD, EBSD and stress-strain data, a significant effect of grain orientation on the stress-induced martensitic transformation is revealed. Strain measurements in pulsed magnetic fields exhibit a substantial impact of grain size on the magnetic-field-induced transformation dynamics. We show that for an optimized microstructure, the maximum cyclic effect in magnetic fields of 1.9 T can be increased by more than 200 % to -4.1 K when a moderate sequential stress of 55 MPa is applied.