Annealing Influence on the Microstructure and Magnetic Properties of Ni–Mn–In Alloys Ribbons

We report on the structure, microstructure and inverse magnetocaloric effect associated with the first-order martensitic phase transition, in Heusler Ni50.0Mn35.5In14.5 alloy ribbons. We have studied the short-time vacuum annealing influence at 1048 K, 1073 K, 1098 K, and 1123 K in these properties. At room temperature, an increase in the degree of structural order for ribbons annealed up to 1098 K was observed, corresponding to cubic L21 austenite phase. Meanwhile, for the sample annealed at 1123 K a monoclinic 10M martensitic phase was detected. A comparison of magnetic entropy change as a function of the applied field, after using zero-field-cooling thermomagnetic and isothermal magnetization measurements, has been made for the sample annealed at 1073 K.