Thermal and magnetic field-induced martensite-austenite transition in Ni50.3Mn35.3Sn14.4 ribbons

Abstract

Thermal and field-induced martensite-austenite transition was studied in melt spun Ni 50.3 Mn 35.3 Sn 14.4 ribbons. Its distinct highly ordered columnarlike microstructure normal to ribbon plane allows the direct observation of critical fields at which field-induced and highly hysteretic reverse transformation starts ͑H = 17 kOe at 240 K͒, and easy magnetization direction for austenite and martensite phases with respect to the rolling direction. Since martensitic transformation from cubic L2 1 -type crystal structure to orthorhombic four-layered martensite ͑4O͒ was observed in Heusler alloys of the ternary system Ni 50 Mn 50−x Sn x , 1 important attention has been devoted to investigate structural transformations, magnetoelastic and magnetocaloric properties in these Ga-free ferromagnetic shape memory alloys. [2][3][4][5][6][7][8][9][10][11] The studies concluded that these materials are prospective for the development of magnetically driven actuators and working substances for magnetic refrigeration. The occurrence of ferromagnetism in both phases has been only found in the narrow composition range of 13ഛ x ഛ 15, 2 and the different magnetization values between martensite and austenite phases leads to a large magnetocaloric effect around the martensitic transition. 7,9 Their crystal structures, as well as the characteristic temperatures of its mutual reversible transformation ͑the starting and finish martensitic and austenitic temperatures, M S , M f , A S , and A f , respectively͒, are very sensitive to small variations in the valence electron concentration per atom e / a, 2,3 and consequently to chemical composition and also depends on the magnetic applied field. The magnetic field can also induce a reverse structural transformation as has been unambiguously demonstrated studying field dependence of x-ray diffraction ͑XRD͒ profiles in bulk polycrystalline Ni 50 Mn 36 Sn 14 alloys, 6 where a field higher than 50 kOe was required to induce around A S a complete phase transition.Rapid quenching by melt spinning offers two potential advantages for the fabrication of these magnetic shape memory alloys: the avoiding, or reduction, of the annealing to reach a homogeneous single phase alloy, and the synthesis of highly textured polycrystalline ribbons. In addition, ribbon shape can be also more appropriate for use in practical devices. Recently, we reported that it was an effective singlestep production process for obtaining Ni 50 Mn 37 Sn 13 ribbons with homogenous chemical composition and strongly ordered microstructure. 12 In this letter, we report on the thermal and magnetic field-induced martensite-austenite transformation, microstructural, and magnetic properties of Ni 50.3 Mn 35.3 Sn 14.4 alloy ribbons.Ribbon flakes of width about 1.5-2.0 mm and length of 6 -7 mm were produced by melt spinning in argon atmosphere at a wheel linear speed of 48 ms −1 starting from arc melted alloys prepared from highly pure elements ͑Ͼ99.9% ͒. Samples were annealed in high vacuum for 2 h at 1073 K. Annealing was followed by wate...

Martensitic Transformation in Ni-Mn-Sn-Co Heusler Alloys

“…Later, Krenke et al studied magnetic and magnetocaloric properties and phase transformations in Ni50Mn50−xSnx alloys with 5 ≤ x ≤ 25 [7]. Rapid solidification techniques, such as melt-spinning, are an alternative to obtain these materials (ribbon shape) [8,9].…”

Effects of Co Additions on the Martensitic Transformation and Magnetic Properties of Ni–Mn–Sn Shape Memory Alloys

“…With the decreasing temperature, these alloys undergo a first-order martensitic transformation (MT) from a high symmetry phase (austenite) to a low symmetry phase (martensite) along with the change of magnetization. Having developed the Ni-Mn-based FSMA, both bulk samples and melt-spun ribbons have been extensively investigated, and therefore, the melt-spinning technique has been widely regarded as an effective method to synthesize highly textured polycrystalline FSMA [6][7][8][9]. It is well known that the magnetic and martensitic transition can be tuned markedly by the partial substitution of Co for Ni into those Mnrich Ni-Mn-X (Sn, In, Sb) alloys.…”

Magnetocaloric effects in magnetic microwires for magnetic refrigeration applications

“…The magnetic entropy change for different applied magnetic field DS M (T,H), as a function of temperature, has been calculated from the Maxwell relationship (Pecharsky and Gschneidner, 1999a,b): The entropy change DS (Figure 19.10) shows a wide peak with a maximum at about 315 K that corresponds to the Curie temperature estimated from magnetization measurement (Figure 19.9). The maximum of DS is slightly above 0.7 J kg À1 K À1 and is comparable to that found in rapidly quenched ribbons (Hernando et al, 2008a). Another group of studied microwires was NiMnIn-based (Vega et al, 2012).…”