Ferromagnetic Martensitic Transition and Magnetocaloric Effect in Ni35Co15-xVxMn35Ti15 (x = 1, 2, 3) All-d-Metal Heusler Alloy Ribbons

In this work, crystal structure, ferromagnetic martensitic transition, and magnetocaloric effect were investigated for Ni35Co15-xVxMn35Ti15 (x = 1, 2, 3) all-d-metal Heusler alloy ribbons. All three samples crystalize pure B2 cubic phase in austenite at room temperature. With increasing V content, the appearance of thermal hysteresis of thermomagnetic curves, together with the negative values of Arrott plots, proves the nature of first-order transition. And normal/reverse martensitic transition temperature (Tt/Tt’) monotonously decreases from 236 (248) K (x = 1) to 82 (110) K (x = 3) and the Curie temperature in austenite (TCA) also decreases. Obvious magnetic-field-induced martensitic transition can also be seen with external magnetic field. Maximum magnetic entropy change values are 17.2, 18.7, 9.6 J/kgK with the magnetic field change of 50 kOe, respectively. The refrigerant capacity (RC) and relative cooling power (RCP), as two important parameters to evaluate the refrigeration performance, can reach 194.7 (240.8), 244.3 (300.0), 162.4 (201.6) J/kg with the magnetic field change of 50 kOe, respectively.