Magnetic and martensitic transformations of NiMnX(X=In,Sn,Sb) ferromagnetic shape memory alloys

Abstract

Martensitic and magnetic transformations of the Heusler Ni50Mn50−yXy (X=In, Sn and Sb) alloys were investigated by differential scanning calorimetry measurement and the vibrating sample magnetometry technique. In all these alloy systems, the austenite phase with the ferromagnetic state was transformed into the martensite phase, which means that these Heusler alloys have potential as Ga-free ferromagnetic shape memory alloys (FSMAs). Furthermore, multiple martensitic transformations, such as two- or three-step martensitic transformations, occur in all these alloy systems. It was confirmed by transmission electron microscopy observation that the crystal structure of the martensite phase is an orthorhombic four-layered structure which has not been reported in other FSMAs. Therefore, the present Ga-free FSMAs have the great possibility of the appearance of a large magnetic-field-induced strain.

Martensitic transitions and the nature of ferromagnetism in the austenitic and martensitic states ofNi−Mn−Snalloys

“…Data from literature are also included in the diagram. 19,21 T C A decreases slightly with increasing e / a up to e / a Ӎ 8.1. Above this concentration, the system is in the martensitic state at room temperature, and the Curie temperature, now T C M , decreases rapidly with increasing e / a.…”

“…17,18 One also observes martensitic transformations in NiMn-Z Heusler alloys where Z can be a group III or group IV element such as In, Sn, or Sb, namely other than Ga or Al. 19 In a considerable region around the stoichiometric Heusler composition, the structure of Ni 2 MnSn can be L2 1 and DO 3 . The binaries Ni-Mn and Ni-Sn undergo martensitic transformations, whereby the product phases are tetragonal and hexagonal, respectively.…”

Magnetic superelasticity and inverse magnetocaloric effect in Ni-Mn-In

“…17,13 Here we concentrate on the magnetostructural coupling in the ferromagnetic Ni 50.3 Mn 33.8 In 15.9 alloy, which has a Curie point T C = 305 K and transforms martensitically on cooling at M s = 210 K. The other characteristic temperatures defining the temperature limits of the transition are M f = 175 K, A s = 200 K, and A f = 230 K. These temperatures are determined from the calorimetry data in Fig. 1͑a͒.…”

Magnetically Anisotropic Ni₂MnGa Thin Films: Coating Glass and Si Micro-Cantilevers Substrates

“…Such materials include NiMnGa [2] and other alloys [3][4][5][6][7][8] and are produced by a large variety of techniques, such as arc melting [9], melt-spinning [10,11], sputtering [12][13][14] and Pulsed Laser Deposition (PLD) [15][16][17].…”