The study of martensitic transformation and magnetocaloric effect in rare earth Y-doped all-d-metal Ni-Co-Mn-Ti Heusler alloys

• The single phase with B2 structure can be obtained with increasing rare earth Y. • Tailoring efficiently martensitic transformation with increasing rare earth Y. • The ΔS m reaches 6.16(23.7) J/kgK under ΔH = 20(70) kOe, respectively. • The RC reaches 82.5(216.6) J/kg under ΔH = 20(70) kOe, respectively. • Exploring an efficient utilization of high-abundance rare earth Y. The effect of rare earth Y doping on the crystal structure, martensitic transformation and magnetocaloric effect (MCE) of Mn 50-x Y x Ni 30.5 Co 9.5 Ti 10 (x = 0, 0.3, 0.5, 0.7) ribbons have been studied in this work. The sample crystalizes coexistence of B2 and 5 M phases for x = 0, and main B2 phase with the increase of rare earth Y. At the same time, the temperature of martensitic transformation from ferromagnetic state to weak-magnetic state monotonously declines due to enriched rare earth Y-precipitated phase. The maximum magnetic entropy change (ΔS m ) and the maximum refrigerant capacity (RC) can reach 6.16(23.7) J/kgK and 82.5(216.6) J/kg under ΔH = 20(70) kOe, respectively.