A very large value of magnetic entropy change ∣ΔS∣=31J∕kgK was obtained at 201K under 5T in LaFe11.8Si1.2 melt-spun ribbons subjected to a very short-time annealing (2h∕1050°C). This value is much higher than that of a bulk LaFe11.44Si1.56 in this temperature range. The large ∣ΔS∣ is attributed to the first-order thermally induced transition at the Curie temperature TC, and is enhanced even further due to a more homogenous element distribution. With increasing Si concentration, TC is increased and ∣ΔS∣ is decreased due to a weakening or an even disappearance of the first-order magnetic phase transition.

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Giant magnetocaloric effect was observed in Mn1.1Fe0.9P1−xGex (x=0.2, 0.24) melt-spun ribbons. The maximum magnetic entropy change ∣ΔSM∣ of Mn1.1Fe0.9P0.76Ge0.24 reaches 35.4J∕kgK in a field change from 0 to 5 T at around 317 K. This value is superior to that reported for Mn1.1Fe0.9P0.76Ge0.24 synthesized by mechanical alloying (∼30J∕kgK at 306 K). The large magnetocaloric effect results from a more homogenous element distribution related to the very high cooling rate during melt spinning. The excellent magnetocaloric effect properties, the low material cost, and the accelerated aging regime make the melt-spun-type MnFePGe materials an excellent candidate for magnetic refrigerant applications.

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