Structure and magnetic properties of highly dispersed Ni-Mn-Ga powders prepared by spark-erosion

• Type: Article in International Scientific Journal
• Date: 2012

Authors

Perekos, AE (Author) Other; Chernenko, VA (Author) Other; Bunyaev, SA (Author) FCUP; Zalutskiy, VP (Author) Other; Ruzhitskaya, TV (Author) Other; Boitsov, OF (Author) Other; G.N. Kakazei (Author) REIT

Journal

Title: Journal of Applied Physics

Vol. 112

ISSN: 0021-8979

Publisher: American Institute of Physics

Indexing

ISI Web of Knowledge - 3 Citations

Scopus - 16 Citations

Other information

Authenticus ID: P-002-3P4

DOI: 10.1063/1.4764017

Abstract (EN): Highly dispersed powders of Ni50,3Mn30Ga19,7 were prepared by spark-erosion in ethanol, water, and kerosene. Powder particles have mostly spherical shape and broad size distribution, with a maximum around 1 mu m. In the as-prepared state, two series of peaks are observed by x-ray diffraction. They are associated with the disordering of two ordered phases, existed in bulk Ni-Mn-Ga: the high-temperature L2(1) austenitic phase and the low-temperature L1(0) martensitic one. Annealing decreases the half-width of the peaks and increases the L1(0)/L2(1) intensity ratio. Magnetically as-prepared powders demonstrate a clear superparamagnetic behavior that changes to ferromagnetic one after annealing. These properties are quite different from the ones of mechanically dispersed powders and rapidly quenched ribbons of the same composition. The spark-erosion conditions, particularly cooling rates up to 10(9) K/s, lead to the formation of the mixed phase state, much higher atomic disorder, and to the appearance of different types of structural inhomogeneities. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764017]

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7