Processing Effects on the Martensitic Transformation and Related Properties in the Ni55Fe18Nd2Ga25 Ferromagnetic Shape Memory Alloy

• Published in: Nanomaterials (Basel, Switzerland) Vol. 12; no. 20; p. 3667
• Main Authors: Sofronie, Mihaela, Popescu, Bogdan, Enculescu, Monica, Tolea, Mugurel, Tolea, Felicia
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 19.10.2022; MDPI
• Subjects: Alloys; Cooling; Ductility; Entropy; Ferromagnetism; Genetic transformation; Heat; Heat treatment; Heusler FSMA; Investigations; Magnetic fields; Magnetic properties; magnetocaloric effect; magnetoresistive effect; Magnetoresistivity; martensitic transformation; Martensitic transformations; Mechanical properties; Melt spinning; nanostructural processing effects; Phase transitions; Ribbons; Scanning electron microscopy; Shape memory alloys; Software; Temperature; Transformation temperature; Germany
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano12203667

The influence of processing on the martensitic transformation and related magnetic properties of the Ni55Fe18Nd2Ga25 ferromagnetic shape memory alloy, as bulk and ribbons prepared by the melt spinning method and subjected to different thermal treatments, is investigated. Structural, calorimetric, and magnetic characterizations are performed. Thermal treatment at 1173 K induces a decrease in both the Curie and the martensitic transformation temperatures, while a treatment at 673 K produces the structural ordering of the ribbons, hence an increase in TC. A maximum value of the magnetic entropy variation of −5.41 J/kgK was recorded at 310 K for the as quenched ribbons. The evaluation of the magnetoresistive effect shows a remarkable value of −13.5% at 275 K on the bulk sample, which is much higher than in the ribbons.