Enhancement of the martensitic transformation and magnetocaloric effect of Ni-Mn-V-Sn ribbons by annealing treatment

The rapidly solidified Ni41.98Mn42.97V2.08Sn12.97 ribbons are prepared by the melt-spinning technique. The microstructure, martensitic transformation (MT), and magnetocaloric effect of the ribbons are greatly affected by annealing treatment. The equiaxed crystallized grains with the relatively homogeneous size distribution are observed for these ribbons. After annealing, the grain size becomes obviously large, the lattice constants decreases, and the exchange bias effect gets improved. The MT temperatures increase obviously for the annealed ribbons. Large magnetic entropy change (ΔS) is obtained in the annealed Ni–Mn–V–Sn ribbons. The peak values of ΔS in the annealed ribbons are 41.6 and −2.3 J kg−1 K−1 in the vicinity of MT temperature and Curie temperature of austenite, respectively, for the field change of 30 kOe.