The magnetostructural transition and magnetocaloric properties in Fe_(0.6)Mn_(0.4)NiSi_(1-x)Al_x alloys

摘要

The Fe_(0.6)Mn_(0.4)NiSi_(1-x)Alx (x = 0, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, and 0.12) alloys were prepared by arc melting and annealed at 1073 K for 90 h. With increasing Al contents, the structure of Fe_(0.6)Mn_(0.4)NiSi_(1-x)Al_x. changes from TiNiSi-type to Ni_2In-type at room temperature, while the Curie temperature decreases from 390 K to 136 K. Although the refrigerant capacity is relatively small, about 126 J/kg, the maximum isothermal entropy change reaches a value of -ΔS_(max) = 52.9 J/(kg K) under 5 T for x = 0.04. At the same time, the alloys have great corrosion resistance. From x = 0 to 0.12, samples can be tuned from a second-order to a first-order and then to a second-order phase transition. It is worth noting that there is no magnetic hysteresis for all samples although they experience structural phase transition. The structural and magnetic phase diagrams of the Fe_(0.6)Mn_(0.4)NiSi_(1-x)Al_x system have been figured out. The results indicate that the relatively large magnetocaloric effects with no magnetic hysteresis and good corrosion resistance make these alloys a good candidate for magnetic refrigeration near room temperature.