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

• Tipo: Artigo em Revista Científica Internacional
• Data: 2012

Autores

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

Revista

Título: Journal of Applied Physics

Vol. 112

ISSN: 0021-8979

Editora: American Institute of Physics

Indexação

ISI Web of Knowledge - 3 Citações

Scopus - 16 Citações

Outras Informações

ID Authenticus: 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]

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7