Effect of solidification rate on martensitic transformation behavior and adiabatic magnetocaloric effect of Ni50Mn35In15 ribbons

Abstract

Ni50Mn35In15 compound has become an archetype for investigating the functional properties of metamagnetic shape memory alloys. We have fabricated Ni50Mn35In15 melt spun ribbons to study the crystal structure, microstructure, martensitic transformation, magnetic properties and magnetocaloric effect as a function of the ribbon solidification rate controlled by the wheel speed. We have found that an increase of the cooling rate refines the alloy grain size, which, in turn, influences the chemical order of austenite phase and functional properties: ribbons produced at low wheel speed (10, 20 and 30 m/s) present majorly L21 structure associated with higher magnetic entropy change, ∆SM (up to 18.6 J/kgK for a magnetic field change of µ0∆H = 5 T) and Curie temperatures of austenite, TC A , and martensite, TC M (TC A = 309 K and TC M = 199 K) compared with the B2-ordered single phase ribbons (∆SM = 11.3 J/kgK for µ0∆H = 5 T; TC A = 293 K; TC M = 178 K) obtained at higher cooling rates ( 40and 50 m/s). Besides, we have also observed a correlation between the grain size reduction and a shift of the martensitic transformation to lower temperatures. Direct measurements of the adiabatic temperature change have been performed during both the first-and secondorder phase transitions. The results disclose the correlation between structural and magnetic properties of the ribbon and the wheel speed, which opens an innovative tool to adjust the transformation characteristics and magnetocaloric properties through the solidification rate control.

Microstructure engineering of metamagnetic Ni-Mn-based Heusler compounds by Fe-doping: A roadmap towards excellent cyclic stability combined with large elastocaloric and magnetocaloric effects

“…In this case, the slight reduction of │ΔTad│ in Fe8 can result from the aforementioned transition broadening and the heat transfer between matrix and secondary phase. It is worth mentioning that despite the reduction of ΔsT and │ΔTad│ in Fe8, a good agreement with literature values for "Fe-free" Ni-Mn-In of similar transition temperatures and field changes is obtained [47,[58][59][60].…”

Large magnetocaloric effect in rapidly quenched Mn50− x Co x Ni40In10 nanomaterials

“…Another factor causing this difference is the microstructure change of the samples due to melt-spinning. It has been reported previously for Ni-Mn-In (Sn) ribbons that the value of T M→A decreases as the grain sizes decrease [28][29][30]. In melt-spinning, grain sizes can be controlled with wheel speed.…”

Distribution of Transition Temperatures in Magnetic Transformations: Sources, Effects and Procedures to Extract Information from Experimental Data

“…Crystal growth and compositional homogenization is enhanced after annealing of these rapidly quenched systems and, generally, increasing the structural and magnetic transition temperatures [55]. Aguilar-Ortiz et al [56] reported a shift of the martensitic transformation in Ni 50 Mn 35 In 15 ribbons from 300 to 285 K as the crystal size decreases from 7.3 to 0.9 µm. They also found variations in the Curie transition of both austenite and martensite (from 309 to 293 K and from 199 to 178 K, respectively).…”