Effect of Fe on the Martensitic Transition, Magnetic and Magnetocaloric Properties in Ni-Mn-In Melt-spun Ribbons

Abstract

IntroductIonThe Ni-Mn-Y (Y = Ga, In, Sn, and Sb) based ferromagnetic Heusler alloys display first order martensitic transitions from cubic to tetragonal or orthorhombic structure upon cooling. Associated with the martensitic transition observed in these alloys several important functional properties such as shape memory effect, inverse magnetocaloric effect and magnetoresistance have been reported [1][2][3] . The martensitic and magnetic transitions in these alloys are composition dependent as they are highly sensitive to the valence electron concentration per atom (e/a) and Mn-Mn interatomic distances 4,5 . In the case of Indium (In) containing alloys, a large inverse magnetocaloric effect (IMCE) in polycrystalline state and significant magnetic field induced strain (MFIS) in single crystals have been reported 6,7 . Recently rapid quenching or melt spinning technique was attempted in various systems such as Ni-Fe-Ga, Ni-Mn-Y (Y = In, Al, Sn, and Ga) alloys [8][9][10][11] . The melt spinning technique has the advantage of producing strong textured polycrystalline ribbons. In the case of magnetic refrigeration applications the use of refrigerant materials in the form of thin films or ribbons can optimize the heat transfer between the working body and the heat-exchange fluid. Additional advantage of melt spun ribbons is that the thin ribbons reduces the eddy current losses and can be utilised at high frequencies. In the recent past, offstoichiometric Ni-Mn-In ribbons has gained lot of interest due to their intriguing martensitic phase transitions, microstructure, associated magnetic, magnetocaloric properties [12][13][14][15][16][17] . In the present study, off-stoichiometric Ni 47 Mn 40 In 13 ribbon composition which reported a large magnetic entropy change of 32 J/kg-K at RT was chosen and Mn was partially substituted by Fe 18. The objective of this work is to understand the effect of Fe on the martensitic transitions, magnetic and magnetocaloric properties in Ni-Mn-In ribbons. Hence, Ni 47 Mn 40-x Fe x In 13 (x = 1, 2, 3, and 5) ribbons were prepared through melt spinning route and studied. ExpErImEntal WorKFour Ni-Mn(Fe)-In alloys were prepared by arc-melting pure metals in an argon atmosphere. Subsequently they were induction melted in a quartz tube and ejected with a 1 bar pressure difference onto a copper wheel rotating at a surface velocity of 17 m/s. The process was carried out in argon environment. As-quenched ribbons were 1.5 mm -2 mm wide, 5 mm -18 mm long and 40 µm -45 µm thick. As-spun ribbons were annealed at 850 o C for 30 min in vacuum and quenched to room temperature using Argon gas. The crystal structure of the constituent phases were examined using an X-ray diffractometer (PHILIPS3121, Cu-K α λ = 1.54058 Ǻ). The compositions of the ribbons were determined by energy dispersive x-ray spectroscopy (EDX) and were found to be close to the nominal composition. The phase transitions between the martensite and austenite phases were determined by differential scanning calorimetry (DSC) with a cooling/he...

Impact of the Co Doping on the Structure, Magnetic Properties, and Phase Transition in Ni_50-xCo_xMn₃₈Sn₁₂ Ribbons

“…This correlates with the results found in Ni-Fe-Mn-In alloys [18]. Likewise, from the DSC analysis and following the method detailed in Ref.…”

Powder Metallurgy Synthesis of Heusler Alloys: Effects of Process Parameters

“…Carried out under controlled conditions of a vacuum (10 −4 bar), an inert atmosphere (argon) with/without the addition of suitable oxygen getter materials, such as Ta or Ti to prevent oxidation [21], arc/melting ensures compositional homogeneity, resulting in a stable single phase L 2 1 structure. Melt-spinning [22,23,24,25,26] produces highly textured samples with controlled austenitic grain size, suitable for practical applications. In a process in which the alloy melt stream is allowed to solidify rapidly on a fast-rotating (10 m/s to 60 m/s) substrate wheel, the wheel speeds which are an indication of the solidified foil thickness and its solidification rate, influence the magnetostructural phase transformations and characteristics of the alloys [27].…”