Influence of annealing on magnetic field-induced structural transformation and magnetocaloric effect in Ni–Mn–In–Co ribbons

A study of the magnetic field-induced martensitic transformation and magnetocaloric effect in Ni45Mn37In13Co5 and Ni46Mn35In14Co5 ribbons prepared by melt-spinning was carried out. Annealing significantly increases the degree of ordering in the austenite phase, reduces the critical field and hysteresis of the magnetically induced martensitic transformation and increases the magnetically induced shift of martensitic transformation temperatures. For the most In-rich sample, Ni46Mn35In14Co5, annealing at 900 °C for 2 h leads to the formation of Co-rich face-centered cubic γ precipitates. The Curie temperature of the γ phase is about 370 K. The formation of the second phase has little impact on the hysteresis, but broadens the transformation interval and reduces the magnetic entropy change.