Enhanced Field Induced Martensitic Phase Transition and Magnetocaloric Effect in Ni55Mn20Ga25 Metallic Foams
The high surface/volume ratio and mechanical stability under cyclic strain makes polycrystalline Ni–Mn–Ga 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 between 44% and 58%) reduces the temperature span of 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 applications.
Sasso, Carlo Paolo; Zheng, Peiqi; Basso, Vittorio; Müllner, Peter; and Dunand, David C.. (2011). "Enhanced Field Induced Martensitic Phase Transition and Magnetocaloric Effect in Ni55Mn20Ga25 Metallic Foams". Intermetallics, 19(7), 952-956. http://dx.doi.org/10.1016/j.intermet.2011.02.015