Magnetic properties and magnetocaloric effect in Mn42Al50-xFe8+x alloys

The structure, magnetism and magnetocaloric effect in Mn42Al50-xFe8+x are studied in this paper. The Curie temperature (T-C) is tunable in a wide temperature range around the ambient temperature by varying the Fe and Al concentration. The values of T-C are 270 K, 341 K and 370 K, respectively corresponding to the values of x of 8, 10 and 12. The magnetization has a sharp drop around the respective phase transition temperature and no obvious thermal or magnetic hysteresis is found, suggesting that a typical reversible second order phase transition occurs. The maxima of the magnetic entropy change (Delta S-m) under an applied field change of 0-5 T are 2.48 (Mn42Al42Fe16), 2.52 (Mn42Al40Fe18) and 2.40 J.kg(-1).K-1 (Mn42Al38Fe20), which are almost independent of composition. The simple and easy preparation process, the good corrosion resistance and ductility, the reversible second order phase transition, and the low cost of raw material make them attractive candidate for the magnetic refrigerant, although their values of Delta S-m are not very large compared those that of the rare earth based compounds.