The Effect of External Magnetic Field on Microstructure and Magnetic Properties of Melt-Spun Nd-Fe-B/Fe-Co Nanocomposite Ribbons

Abstract

The ribbons Nd2Fe14B/Fe-Co were prepared with the nominal composition Nd16Fe76B8/40% wt. Fe65Co35by the conventional and the developed magnetic field-assisted melt-spinning (MFMS) techniques. Both ribbons are nanocomposites with the smooth single-phase-like magnetization loops. The 0.32 T magnetic field perpendicular to the wheel surface and assisting the melt-spinning process reduces the grain size inside the ribbon, increases the texture of the ribbon, improves the exchange coupling, and, in sequence, increases the energy product(BH)maxof the isotropic powdered samples of MFMS ribbon in ~9% by comparison with that of the ribbon melt-spun conventionally. The grain size reduction effect caused by the assisted magnetic field has also been described quantitatively. The MFMS technique seems to be promising for producing high-performance nanocomposite ribbons.

Magnetic field assisted melt–spinning Nd-Fe-B ribbons and anisotropic bonded NdFeB magnets prepared thereof

“…This crystallographic preferred orientation along c-axis was caused by the shape anisotropy of Fe/Co seeds formed at the beginning step of crystal growth under action of an assisting field [13]. The texture was enhanced in the ribbon melt-spun at the lowest used speed v = 8 m/s and is due to the synchronal effect of two forces creating the texture, the field assisted [10,11,14] and the temperature gradient oriented perpendicularly to the ribbon plane. This gradient was established by the rapid cooling of the melt dropped on the rotating wheel surface [14].…”

“…The quartz tube orifice diameter was fixed at 1.0 mm, the distance between the nozzle and the wheel surface was kept constant by 5 mm. The copper wheel speed was varied in the range of 8 -16 m/s, which was lower than that chosen in [10]. The composition and structure were examined by the X-ray diffraction (XRD) patterns carried out by using SIEMENS D5000 X-ray diffractometer with Cu-K α radiation.…”

“…We proved in Ref. [10] that this configuration can be easily prepared by the magnetic-field-assisted melt-spinning (FAMS) technique. For Nd-Fe-B systems, during the FAMS process, the α-Fe seeds are formed initially on the wheel surface, the hard magnetic Nd-Fe-B grains are then grown on the seeds along the temperature gradient perpendicular to the ribbon plane.…”

“…This crystalline growth process creates (00l) texture of ribbons. The magnetic field increases the volume energy of seeds and thus decreases their critical size and, consequently, decreases the average grain size [10][11][12]. These textured ribbons should become a good starting material for preparing anisotropic magnets.…”

Glass Forming Ability, Thermal Stability, and Magnetic Properties of FeCoNiBSi Alloys with Different B Contents

“…Soft magnetic amorphous alloys have been well known in the various electromagnetic applications, such as sensors, transformers, and electronic and power devices [1][2][3] because of their excellent magnetic properties including the high saturation magnetization, ultrahigh magnetic permeability, and low coercive force [3][4][5]. Fe 40 Ni 38 Mo 4 B 18 (Metglas2826MB) amorphous alloy was the earliest magnetic material [6,7] applied to the acoustomagnetic antitheft label and received a lot of attentions and debates.…”