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The effect of cobalt doping on martensitic transformations and magnetic properties of the Ni50-xCox Mn37Sn13 (x = 1, 2, 3) magnetic shape memory alloys obtained by melt spinning in form of ribbons is studied. The crystallographic structure of all ribbons at room temperature is austenite cubic L21. SEM micrographs indicate the formation of textured ribbons with columnar grains growing up perpendicular to the ribbons plane. For all ribbons, DSC cyclic scans reveal the martensitic transformation on cooling and the reverse austenitic transformation on heating below room temperature. In addition, they indicate that martensitic transformation temperatures decrease with increasing cobalt content. Thermomagnetic curves reveal the coexistence of AFM and FM exchange interactions at low temperatures. Likewise, the magnetization change (∆M) between martensite and austenite phase, as well as the austenite Curie temperature (TC A), increase with greater cobalt amount in ribbons. Structural transformations are also sensitive to the external applied magnetic field. This fact suggests that the structural transformations temperatures of the ribbons could be tuned to the desired functional temperature by controlling the cobalt amount replacing Ni. as well as changing the applied magnetic field which could lead to the enhancement of the magnetic properties.

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