Magnetic properties and phase components in amorphous (Fe1−xNdx)81.5B18.5 alloys after crystallization

Abstract

Magnetic properties and phase components for amorphous (Fe1−xNdx)81.5B18.5 alloys after crystallization were studied systematically. The crystallization temperature of the amorphous alloys is found to increase first with increasing Nd concentration x, goes through a maximum at x=0.11, then decreases. The crystalline phases of the samples annealed at different temperature were identified by X-ray diffraction and thermomagnetic measurements. It is observed that the crystallized (Fe1−xNdx)81.5B18.5 alloys with 3–6 at% Nd additions consist of Nd2Fe14B, Fe3B and αFe. The concentration dependence of the intrinsic coercivity iHc and maximum energy product (BH>)max are found to have a maximum at the concentration near x=0.055. A room temperature coercive field of 2.9 kOe and an energy product of 13.3 MGOe are obtained in Fe77Nd4.5P18.5 alloy annealed at 670°C for a short time. These FeNdB alloys with fewer Nd concentration would be used as an inexpensive bonded magnets, due to its higher values of Br and (BH)max.