Regensburg 2016 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 34: Topical session: Caloric effects in ferroic materials IV - Heuslers

MM 34.3: Vortrag

Mittwoch, 9. März 2016, 12:30–12:45, H39

Magnetocaloric and microstructural properties of Half-Heusler-type alloys — •Andreas Taubel, Tino Gottschall, Konstantin P. Skokov, Iliya A. Radulov, and Oliver Gutfleisch — Materials Science, TU Darmstadt, 64287 Darmstadt, Germany

Magnetocaloric refrigeration offers an efficient and environmentally friendly alternative to conventional gas compression cooling. Besides the well-known Gd-Si-Ge and La-Fe-Si systems, Heusler alloys and their related Half-Heusler and MM^′X materials come into focus. The Mn-Ni-Ge system exhibits a martensitic phase transition from its high temperature hexagonal phase to its low temperature orthorhombic phase with a broadly tunable transition temperature when partially substituting Fe for Mn or Ni. Previous studies already showed a sharp transition with low hysteresis and considerable changes in magnetization during the transition. In this work, we could obtain very large isothermal entropy changes ΔS_m of up to -37.8 Jkg⁻¹K⁻¹ based on magnetic measurements of small single pieces. However the high volume change of 2.7 % results in an embrittlement of large particles into several smaller grains. For this reason bonding of the material with a polymer epoxy was carried out in order to enable direct measurements of ΔT_ad and to evaluate the possibility for its usage under real conditions in a magnetocaloric cooling device.

Supported by DFG Priority programme 1599