Coercivity mechanism of sintered NdFeB magnets having high coercivities

1990 ◽  
Vol 67 (9) ◽  
pp. 4750-4752 ◽  
Author(s):  
A. Fukuno ◽  
K. Hirose ◽  
T. Yoneyama
Keyword(s):  
Ndfeb Magnets ◽  
Coercivity Mechanism

Relation between Initial Magnetization Curve and Grain Size of Nanocrystalline NdFeB Magnets

2014 ◽  
Vol 802 ◽  
pp. 558-562 ◽  
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A.S. da Silva ◽  
José Adilson de Castro
Keyword(s):  
Grain Size ◽  
Magnetization Curve ◽  
Volume Fraction ◽  
Domain Size ◽  
Single Domain ◽  
Ndfeb Magnets ◽  
Initial Susceptibility ◽  
Initial Magnetization ◽  
Coercivity Mechanism

The volume fraction of the single domain size particles can be directly estimated from the initial magnetization of thermally demagnetized magnets. Multi-domain grains present initial magnetization curve with high initial susceptibility, whereas single-domain grains present low susceptibility initial magnetization curve. In the case of single domain size particles, the coercivity mechanism is coherent rotation and the Stoner-Wohlfarth (SW) model can be applied. From the initial magnetization curve of magnets, the volume fraction of grains with diameter less than 0.3 micrometers can be estimated in NdFeB magnets. This is possible because the Nd2Fe14B phase is single domain below 0.3 micrometers.

Study on Coercivity Mechanism of the Sintered NdFeB Magnets by Zr Addition

2011 ◽  
Vol 179-180 ◽  
pp. 751-756
Author(s):  
Peng Yue Zhang ◽  
Hong Liang Ge ◽  
Min Xiang Pan ◽  
Qiong Wu ◽  
Hang Fu Yang ◽  
...  
Keyword(s):  
Xrd Analysis ◽  
Pole Density ◽  
X Ray Diffraction ◽  
Ndfeb Magnets ◽  
X Ray ◽  
Microstructural Parameters ◽  
Zr Addition ◽  
Density Factor ◽  
Coercivity Mechanism ◽  
Microstructure And Magnetic Properties

The effects of Zr addition on the microstructure and magnetic properties of the sintered NdFeB magnets were investigated by X-ray diffraction (XRD) and BH magnetic tester. The XRD analysis showed that both the Zr-free and Zr-doped samples are composed of main amount of Tetragonal phase Nd2Fe14B (P42/mnm) and trace amount of Nd-rich phase, but adding Zr reduces significantly the values of pole density factor of (004), (006) and (008) crystal faces for the sintered Nd(Fe,Zr)B magnets estimated by Horta-formula. Accordingly, the coercivity of the sample with Zr addition is reduced from 2038 kA/m down to 1951 kA/m. The study of the Kronmüller-plot shows that the nucleation is the dominating mechanism for the magnetization reversal in these two kinds of magnets, and two microstructural parameters of αk and Neff are obtained also.

Nucleation as Coercivity Mechanism in NdFeB Magnets

2014 ◽  
Vol 775-776 ◽  
pp. 437-442 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Domain Wall ◽  
Coercive Field ◽  
Square Root ◽  
Ndfeb Magnets ◽  
Single Domain Particle ◽  
Wall Displacement ◽  
Melt Spun ◽  
Coercivity Mechanism

In the first part of this article, the SW-CLC (Stoner-Wohlfarth with CLC modification) model is discussed for nanocrystalline magnets, as melt-spun exchange coupled NdFeB. In the second part, the effect of grain size of coercivity for large grain size, above the single domain particle size, is addressed. The Kondorsky law observed for large grain size only can be due to domain wall displacement phenomena, where there is nucleus expansion. There are two main situations, one for nanocrystalline grain size, where the SW-CLC model is obeyed, and other for large grain size, where the coercive field decreases proportionally to the square root of the grain size.

MAGNETIZATION PROCESSES IN MELT SPUN NdFeB-MAGNETS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-655-C8-656 ◽  
Author(s):  
A. Handstein ◽  
J. Schneider ◽  
U. Heinecke ◽  
R. Grössinger ◽  
H. Sassik
Keyword(s):  
Ndfeb Magnets ◽  
Melt Spun ◽  
Magnetization Processes

Selective and efficient extraction of Nd from NdFeB magnets via ionization in LiCl-KCl-CdCl2 melt

2021 ◽  
Vol 860 ◽  
pp. 158424
Author(s):  
Younghwan Jeon ◽  
Jungho Hur ◽  
Gwan Yoon Jeong ◽  
Sungjune Sohn ◽  
Jaeyeong Park
Keyword(s):  
Ndfeb Magnets ◽  
Efficient Extraction

A HYBRID MODEL ON HYSTERESIS LOOP AND COERCIVITY IN NANOSTRUCTURED PERMANENT MAGNETS

2006 ◽  
Vol 05 (04n05) ◽  
pp. 627-631 ◽  
Author(s):  
M. J. SUN ◽  
G. P. ZHAO ◽  
J. LIANG ◽  
G. ZHOU ◽  
H. S. LIM ◽  
...  
Keyword(s):  
Thin Films ◽  
Domain Wall ◽  
Grain Boundary ◽  
Magnetic Moment ◽  
Permanent Magnets ◽  
Hysteresis Loops ◽  
Bulk Materials ◽  
Rotational Model ◽  
Moment Distribution ◽  
Coercivity Mechanism

A simplified micromagnetic model has been proposed to calculate the hysteresis loops of nanostructured permanent magnets for various configurations, including thin films, exchange-coupled double-layer systems and bulk materials. The reversal part of the hysteresis is based on the Stoner–Wohlfarth coherent rotational model and the coercivity mechanism is due mainly to the motion of the transition region (a domain wall like magnetic moment distribution in the grain boundary). The elements of nucleation and pinning models are also incorporated.

Corrosion resistance of NdFeB magnets coated by Al

1996 ◽  
Vol 32 (5) ◽  
pp. 4407-4409 ◽  
Author(s):  
N.C. Ku ◽  
C.-D. Qin ◽  
C.C. Yu ◽  
D.H.L. Ng
Keyword(s):  
Corrosion Resistance ◽  
Ndfeb Magnets

Coercivity and Thermal Stability Enhancement for Spark-Plasma-Sintered Nanocrystalline NdFeB Magnets With Dy2O3 and Zn Additions

2015 ◽  
Vol 51 (11) ◽  
pp. 1-4
Author(s):  
Z. W. Liu ◽  
L. Z. Zhao ◽  
S. L. Hu ◽  
H. Y. Yu ◽  
X. C. Zhong ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ndfeb Magnets ◽  
Spark Plasma ◽  
Stability Enhancement

Nd2Fe17 nanograins effect on the coercivity of HDDR NdFeB magnets with low boron content

2012 ◽  
Vol 19 (3) ◽  
pp. 236-239 ◽  
Author(s):  
Ai-zhi Sun ◽  
Shen Wu ◽  
Wen-huan Xu ◽  
Jin Wang ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Boron Content ◽  
Ndfeb Magnets
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