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Magnetic Properties and Consolidation Techniques for REFeB Permanent Magnets Based on Melt Spun Nanocrystalline Powders

Author: HuangHuaYong
Tutor: LiuZhongWu
School: South China University of Technology
Course: Materials Science
Keywords: REFeB Spark Spark Plasma Sintering Thermal deformation CPM repression Dilute magnetic materials
CLC: TM273
Type: Master's thesis
Year: 2011
Downloads: 111
Quote: 1
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Abstract


As an integrated magnetic alloy NdFeB permanent magnet materials are best, in aerospace, machinery, electronics, communications and other national key scientific and economic sector plays an important role. Rapidly quenched NdFeB nanocrystalline powders with high remanence and low rare earth content is very suitable for preparing low-cost high-performance rare earth permanent magnets. By rapid quenching nanocrystalline REFeB powder raw materials were prepared using the new preparation of nanocrystalline isotropic and anisotropic magnetic rare earth permanent magnets become an important research direction. In this paper, quenched NdFeB nanocrystalline Nd ( 13.70Co 6.7 Ga 0.5 Fe 73.5 B 5.6 (at%) and micron-scale iron as raw material, the use of a spark discharge plasma sintering (SPS) was prepared nanocrystalline isotropic NdFeB permanent magnet, spark discharge plasma sintering (SPS) and heat distortion (HD) Preparation anisotropic nanocrystalline NdFeB permanent magnets. detailed study of the SPS and HD isotropic and anisotropic magnets process on microstructure and magnetic properties. exploratory speed repression by powder technology (HVC) Nanocrystalline NdFeB magnets, while the effects of different Pr content spun nanocrystalline Pr / Pr 2 Fe 14 B dilute magnetic alloys and exchange coupling. discharge spark plasma sintering process on nanocrystalline microstructure of NdFeB magnets and magnetic properties can have a significant impact. SPS temperature less than 700 ℃, the magnet maintained rapid quenching nanocrystalline powders, fine and uniform grain sintering temperature is higher than 700 ℃, due to the plasma spark discharge sintering temperature field formed, coarse grain zone first formed in the grain boundaries due to grain interior maintains fine grain zone structure, spark plasma sintered magnet spark formation CGHAZ white and fine grain microstructure area. SPS sintering pressure and holding time increases in a certain range improves the microstructure and magnetic properties of the magnet can. SPS technology research prepared by the best magnetic properties of the magnet: B r = 0.82T, H (< / sub> cj0 = 1516kA / m, electric spark plasma sintering and hot deformation anisotropy successfully prepared single-phase and two-phase nanocrystalline permanent magnets NdFeB NdFeB magnets crystal density reached 83% of theoretical density. powder high speed (BH ) max = 116kJ / m 3 . studied the SPS magnet from the center to the edge in different parts of the organization and magnetic properties. magnetic coercivity larger rims, the center left magnetic high energy product at the center of the radius at the best. prepared by SPS composite magnetic isotropic phase and did not enhance the exchange coupling magnetic, contrary increase the static magnetic exchange interaction, reducing the performance of the magnet. put. after hot deformation of NdFeB (004), (105), (006) and (008) peaks were enhanced magnetic grains of fine grain zone occurred partially oriented. thermal deformation deformation significantly affect the properties of the magnet, when the deformation amount of 68%, the best magnetic properties can Br = 1.27T, Hcj = 988kA / m, (BH) max = 274kJ / m 3 . thermal deformation only a substantial increase in the magnetic properties of the magnet and the magnet to enhance the exchange coupling. CPM suppression technique to suppress the nano material effective to maintain the coercivity and the grain size of the powder pressing process speed improvement is expected to be prepared by high Performance nanocrystalline NdFeB permanent magnets in the rich Pr, Pr / Pr 2 Fe 14 B (at%) in dilute magnetic alloys, Pr content increases to improve the material's coercive force, the coercivity by the Pr 2.55 Fe 14 B of 999 kA / m increased to Pr 6 Fe 14 B (at%) of 2114kA / m, confirmed between the grains of the hard magnetic phase paramagnetic phase decreased with the increasing of the exchange coupling, the alloy more close to the Stoner-wohlfarth models meet alloy body

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CLC: > Industrial Technology > Electrotechnical > Electrical materials > Magnetic materials,ferrite > Permanent magnet materials, permanent magnet
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