Microstructure and magnetic properties of Ni50Mn37Sn13 Heusler alloy ribbons

Abstract

The Heusler alloy Ni 50 Mn 37 Sn 13 was successfully produced as ribbon flakes of thickness around 7-10 m melt spinning. Fracture cross section micrographs in the ribbon show the formation of a microcrystalline columnarlike microstructure, with their longer axes perpendicular to the ribbon plane. Phase transition temperatures of the martensite-austenite transformation were found to be M S = 218 K, M f = 207 K, A S = 224 K, and A f = 232 K; the thermal hysteresis of the transformation is 15 K. Ferromagnetic L2 1 bcc austenite phase shows a Curie point of 313 K, with cell parameter a = 0.5971͑5͒ nm at 298 K, transforming into a modulated 7M orthorhombic martensite with a = 0.6121͑7͒ nm, b = 0.6058͑8͒ nm, and c = 0.5660͑2͒ nm, at 150 K. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2832330͔Ferromagnetic shape memory alloys ͑FSMA͒ are of considerable interest because of their exceptional magnetoelastic properties.1-3 The shape memory effect can not only be controlled by changing the temperature, as it occurs in traditional shape memory alloys, but also by varying the magnetic field up to moderate field values. The latter makes them of noteworthy interest for developing new thermal or magnetically driven actuators. 4Among the Heusler alloys that exhibit magnetic shape memory effect, the most extensively studied are those of the Ni-Mn-Ga system. However, to overcome some of the problems related to practical application, such as the high cost of gallium and the low martensitic transformation temperature that they usually present, the search for Ga-free alloys has been recently attempted. Martensitic transformation in ferromagnetic Heusler Ni 50 Mn 50−x Sn x alloys with 10ഛ x ഛ 16.5 was first reported by Sutou et al. 5 Later, Krenke et al. studied phase transformations and magnetic and magnetocaloric properties of the Ni 50 Mn 50−x Sn x alloy series with 5 ഛ x ഛ 25. 6,7 Samples with x = 0.13 and 0.15 are ferromagnetic in the martensitic state undergoing a first order martensitic-austenitic structural transition at a temperature below the respective Curie points of both phases. At room temperature, the alloy with x = 0.13 is martensitic, and the martensite-austenite transformation occurs around room temperature. Brown et al. 8 12 They report magnetic entropy changes up to 10.4 J / kg K at 10 kOe for x = 7. Ni-Mn-Sn system is, therefore, of prospective importance as FSMA and as promising magnetic refrigerant alloy. In all these cases, alloys were produced as bulk polycrystalline samples.In this work we produced, as far as we know for the first time, Ni-Mn-Sn alloys by rapid solidification. This procedure offers several potential advantages for the fabrication of the shape memory materials such as avoiding the homogenization annealing step to reach a single phase alloy and the synthesis of highly textured polycrystalline samples. Moreover, ribbon shape is appropriate for direct use in practical devices. In view of its interesting properties, 6,7 we have selected the alloy Ni 50 Mn 37 Sn 13 and studied its microstr...

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

“…Traces of secondary or spurious phases were not detected. Structures of both phases coincide with the found ones in as-spun ribbons, 12 but the modulation of the orthorhombic martensite is different to that found in bulk materials with closer compositions such as Ni 50 Mn 36 Sn 14 ͑4O͒ ͑Refs. 4 and 5͒ or Ni 50 Mn 37 Sn 13 ͑10M͒.…”

“…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 water quenching.…”

“…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.…”

Annealing Effect on Martensitic Transformation and Magneto-Structural Properties of Ni-Mn-In Melt Spun Ribbons

“…Recently, it has been reported in literature that ferromagnetic shape memory alloys in the Heusler Ni 50 Mn 50-y X y (X= Sn, In) systems can be produced as single-phase materials by rapid solidification using melt spinning technique [1,2]. The ribbon flakes obtained usually crystallize in a cubic L2 1 -type austenitic phase.…”

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].…”