Magnetocaloric Effect of Ni44Co6Mn40CuxSn10-x Quinary Alloy Comes from the Martensitic Transformation

Abstract

The structure, martensitic transition and magnetic properties of Ni44Co6Mn40CuxSn10-x quinary alloy are investigated systematically. The substitution of Cu for Sn is found to reduce the symmetry of crystal structure, showing an evolution from cubic to tetragonal phase at room temperature. Two magnetic transitions were observed in the alloys, martensitic transition and Curie transition. The critical temperatures of martensitic transformation are found to increase nearly linearly with increasing valence electron concentration caused by Cu substitution for Sn, while Curie temperature of the austenitic phase decreases with the increasing Cu content in the alloys. The Ni44Co6Mn40CuxSn10-x alloys have a large magnetic entropy change across the martensitic transition, reaching 26.8 Jkg-1K-1 under a field change of 3T, because of the strong coupling between structure and magnetism, which shows a great applicable prosperity in magnetic refrigeration technology.