Effet magnétocalorique dans les alliages de Heusler de Ni-Mn-X (X= Ga, In).

The positive magnetocaloric effect (MCE) in Ni(2+x)Mn(1-x)Ga (x= 0.33, 0.36, 0.39), Ni(50.2)Mn(39.8)In(10), Ni(49.4)Mn(41.4)In(9.2), Ni(48)Mn(43.3)In(8.7) Heusler alloys close the Curie points and the negative and positive MCE near the metamagnetostructural (MMS) transition and the Curie point in Ni(45)Co(5)Mn(36.5)In(13.5) Heusler alloy has been measured by a direct method. For the magnetic field change= 2 T, the maximal adiabatic temperature change at the Curie point in Ni(2+x)Mn(1-x)Ga alloys is larger than 0.6 K and the maximal at the Curie point in Ni(50.2)Mn(39.8)In(10) is equal to 1.15 K at 318 K. For Ni(45)Co(5)Mn(36.5)In(13.5) alloy, the maximal value of adiabatic temperature change= 1.68 K (for the same magnetic field change= 2T) is observed at the MMS phase transition temperature.