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Influence of microstructure on the magnetocaloric behaviour of Heusler alloys at their martensitic transition.

Solzi M., Cugini F., Porcari G., Rimoldi T., Orsi D., Fabbrici S., Albertini F.
  Lunedì 11/09   14:30 - 18:30   Aula A224   II - Fisica della materia
Magnetic refrigeration based on the magnetocaloric effect (MCE) represents an efficient and environmentally friendly realistic alternative to the current gas-based refrigeration technology. In Heusler alloys, the MCE is large across the martensitic phase transition and its intensity is strongly influenced by the transition width. Magnetic and calorimetric analysis together with optical microscopy are compared to correlate the transition broadening with microscopic features of a $Ni$ - $Co$ - $Mn$ - $Ga$ - $In$ Heusler alloy. The three techniques give the same temperature behaviour of the transition. Microscopy analysis of different sample areas and during cycles in temperature reveals the spatial homogeneity of the transition width and its reproducibility.