Improved energy product in grained aligned and sintered MRE2Fe14B magnets (MRE=Y+Dy+Nd)

Abstract

Magnetism in grain-boundary phase of a NdFeB sintered magnet studied by spin-polarized scanning electron microscopy Appl. Phys. Lett.Analysis of the demagnetization process of Nd-Fe-B sintered magnets at elevated temperatures by magnetic domain observation using a Kerr microscope Sintered ͓Nd 0.45 ͑Y 3 Dy 1 ͒ 0.25 ‫ء‬ 0.55 ͔ 2.8 Fe 14 B magnets were prepared for the first time. Magnetic properties and microstructures of the magnets were investigated by magnetic measurements and electron microprobe analysis. The microstructure consists of a MRE 2 Fe 14 B ͑2-14-1͒ phase matrix having a grain size of ϳ10 m and a RE-rich grain boundary phase. However, sintering resulted in segregation of Y to the inner and Nd to the outside of the 2-14-1 grains. The magnet has a room temperature ͑BH͒ max of 25.4 MGOe, which is two times higher than that of the isotropic melt spun ribbons with similar compositions. The temperature coefficients of Br ͑␣͒ and Hcj ͑␤͒ for the magnet are Ϫ0.150 and −0.632% /°C from 27 to 127°C, respectively. These temperature coefficients, especially for ␤, are also much higher than those of melt spun ribbons. The composition segregation in the 2-14-1 grains is believed to be responsible for the higher temperature coefficients.

Phase Formation, Microstructure, and Magnetic Properties of Nd14.5Fe79.3B6.2 Melt-Spun Ribbons with Different Ce and Y Substitutions

“…Meanwhile, the high-abundant and cheap rare earth metals La, Ce, and Y were not used effectively in the production of Nd-Fe-B magnets. Therefore, the integrated utilization of rare earth metals in Nd-Fe-B magnets is a promising way to achieve the sustainable development of Nd-Fe-B magnets [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. However, the magnetic properties of Nd-Fe-B magnets with La, Ce, and Y have deteriorated unavoidably through the traditional fabrication technology because intrinsic magnetic properties of La 2 Fe 14 B, Ce 2 Fe 14 B, and Y 2 Fe 14 B phases are inferior to those of Nd 2 Fe 14 B, Dy 2 Fe 14 B, and Tb 2 Fe 14 B phases [ 35 ].…”

“…However, the magnetic properties of Nd-Fe-B magnets with La, Ce, and Y have deteriorated unavoidably through the traditional fabrication technology because intrinsic magnetic properties of La 2 Fe 14 B, Ce 2 Fe 14 B, and Y 2 Fe 14 B phases are inferior to those of Nd 2 Fe 14 B, Dy 2 Fe 14 B, and Tb 2 Fe 14 B phases [ 35 ]. Recently, different fabrication technologies (e.g., double main phase method, dual alloy method, and grain boundary diffusion method) and microstructure optimization (e.g., grain boundary restructure) were developed to improve magnetic properties of Nd-Fe-B magnets with La, Ce, and Y [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ].…”

“…In particular, the magnetic performance of Y and/or Ce substituted Nd-Fe-B alloys were investigated in the literature [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Chen et al [ 26 ] reported that Nd 9-x Y x Fe 72 Ti 2 Zr 2 B 15 nanocomposite ribbons exhibited high coercivity (923.4 kA/m).…”

“…The remarkable increase of the coercivity of magnets with x = 2 indicated that Y-Ce co-substitution could improve the magnetic properties of Nd-Fe-B magnets. The experimental results [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ] indicate the significant effect of alloy composition, microstructure, and fabrication technology on the magnetic properties of Nd-Fe-B alloys with Ce and/or Y substitution. In order to understand further the effect of phase formation and microstructure on magnetic properties of Nd-Fe-B alloys with Ce and Y co-substitution, phase structure, microstructure, and magnetic properties of (Nd 1-2x Ce x Y x ) 14.5 Fe 79.3 B 6.2 alloys were studied experimentally in this work.…”

Enhanced Thermal Stability of Nd–Fe–B Sintered Magnets by Intergranular Doping Y72Co28 Alloys

“…The origin of the improved thermal stability is that Y 2 Fe 14 B possesses a weak temperature dependence on H A [9]. However, partial substitution of Pr/Nd with Y in sintered magnets does a little to the improvement of thermal stability, attributing to the composition segregation in the 2-14-1 grains [10]. The reason is that melt-spun ribbons possess a relatively homogenous RE distribution in the microstructure, which is frozen-in during the melt-spinning process due to the very high cooling rate.…”