Magnetic phase diagrams for Fe54Al36Nb10 and Fe48Al32Nb20 alloys

ZAMORA, L.E.; PÉREZ ALCÁZAR, G.A.; TABARES, J.A.; BETANCUR, J.D.; SIVES, FLAVIO R.; JAEN, J.; GRENECHE, J.M.; MARCO, J.F.; GONZÁLEZ, J.M.

JOURNAL OF PHYSICS - D (APPLIED PHYSICS)

IOP PUBLISHING LTD

Lugar: Londres; Año: 2008 vol. 41 p. 1 - 9

0022-3727

Two nanostructured powdered alloys, Fe54Al36Nb10 and Fe48Al32Nb20, were milled from elemental powders in a planetary high-energy ball mill for 12, 24 and 36 h. X-ray diffraction (XRD), magnetic measurements and 57Fe M¨ossbauer spectrometry were used to investigate the structural, magnetic and hyperfine properties of the alloys. All samples show paramagnetic behaviour at room temperature but the increasing milling time favours highly disordered alloys which consist of a random packing of nanoclusters. The alloys milled for 36 h show ferromagnetic behaviour and the Curie temperature was found to decrease from 178K down to 39K for 10 at% and 20 at% Nb, respectively. Their corresponding magnetic phase diagrams are established, showing thus ferromagnetic, paramagnetic and superparamagnetic or cluster behaviour.