Martensitic Transformation, Magnetic and Mechanical Characteristics in Unidirectional Ni-Mn-Sn Heusler Alloy

A textured structure of Ni-Mn-Sn Heusler alloy with [001] preferred orientation has been grown by the directional solidification method. The crystal exhibits a single austenite phase L2(1) cubic structure (a = 5.997 angstrom) at room temperature. Magnetization and electronic transport measurements reveal the phase transformation characteristics. The maximum values of magnetic entropy change determined by Maxwell's thermodynamic relation during the structural and magnetic phase transformations are 3.5 J/kg center dot K and -4.1 J/kg center dot K, and the total effective refrigerant capacity reaches about 314 J/kg (5 T). The evident reduction in hysteresis loss and broad operating temperature window provide a greater prospect for improving the cyclic stability of refrigeration and optimizing the application of such a magnetic refrigeration material. Both magnetoresistance (-18%, 5 T) and exchange bias field (302 Oe, 2 K) have also been investigated to understand the nature of phase transformations and exchange interactions. Furthermore, as the material exhibits excellent mechanical properties (1068 MPa, 9.0%), our experimental results provide a new reference for the application of Ni-Mn-Sn Heusler alloys.