Enhanced field induced martensitic phase transition and magnetocaloric effect in Ni55Mn20Ga25 metallic foams
نویسندگان
چکیده
Thehigh surface/volumeratio andmechanical stabilityunder cyclic strainmakespolycrystallineNieMneGa metallic foams attractive for magnetic refrigeration. By means of comparison with a polycrystalline bulk material, we have demonstrated that the porous structure of Ni54.8Mn20.2Ga25.0 open-cells metallic foams (porosity varying between44% and58%) reduces the temperature spanof the phase transition and increases the magnetocaloric effect (MCE). MCE was investigated using calorimetry in a magnetic field. Temperature scan and isothermal experiments have shown a 0.8 K T 1 shift of the phase transition temperature and a maximum irreversible entropy change of 2.5 Jkg 1 K 1. The results indicate that metallic foams can represent a good approach for enhancing field induced phase transitions in magnetic refrigeration
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