Structural and magnetic phase transition in quinary Ni45Co5(Mn, In, Sn)50 Heusler alloy

The structure, magnetic phase transition and martensitic transformation of quinary Ni45Co5(Mn, In, Sn)50 Heusler alloy are investigated systematically. X-ray diffraction reveals that there are two kinds of typical structure in alloys, the martensite phase with tetragonal structure and the austenite with cubic structure. Furthermore, it is found that Mn content plays an important role in the evolution of the crystal structure of quinary alloys, making the structure of alloys transform the cubic phase to tetragonal with increasing Mn content, and the threshold of structure transformation is about the Mn content of 35%. The temperature dependence of magnetization indicates that the tetragonal phase usually exhibits a low magnetization, while the cubic corresponds to a high magnetization. Particularly, the strong coupling between magnetism and structure occurs in Ni45Co5Mn40InxSn10−x alloys, and the alloys exhibit a large magnetic entropy change of 22.5 J kg−1 K−1 in martensitic transformation, making it a good candidate for magnetic refrigeration materials.