Magneto-mechanical coupling in ferromagnetic shape memory alloys: Mechanical experimental investigation under magnetic field in NiMnGaCu alloy

Abstract

Ferromagnetic shape memory alloys attracted increasing interest as multicaloric materials for solid state refrigeration. The most effective field coupling is achieved through the combination of the magnetic and mechanical induction of thermoelastic martensitic transformation. In the present work, we present an experimental investigation on NiMnGaCu polycrystalline cast alloy, by means of an experimental setup for compression tests in isothermal conditions under a longitudinal magnetic field. The setup has been ad hoc designed and developed specifically for this purpose. In this way, we can measure the elastocaloric and magnetocaloric effect at the same time. Moreover, the evolution of the entropy changes ΔS and the functional caloric parameters vs the magnetic field is evaluated. The application of magnetic field seems to act like a supplementary mechanical longitudinal stress. These preliminary results are fundamental to achieve a comprehensive understanding and modeling of coupled multicaloric phenomena.