Preparation of Anisotropic Nd-Lean Nd-Fe-B Magnets with Improved Coercivity

Anisotropic bulk nanocrystal Nd-lean Nd-Fe-B magnets were prepared by hot-pressing the mixture of Nd11.5Fe81.5Nb1B6 melt-spun ribbons and pure Zn powder and subsequent hot-deforming. The effects of deformation on the magnetic properties and microstructure were also studied. The magnetic properties increased significantly for hot-deformed (HD) samples due to the formation of good c-axis texture with increasing deformation. The remanence Mr and maximal energy product (BH)m increased and reached their maximal values at 65% deformation due to the increasing orientation. On the other hand, the grains increased and were elongated normal to the press direction gradually with increasing deformation. The variation trend was similar to that of traditional Nd-Fe-B magnets. However, there was an obvious improvement for coercivity in the initial stage of hot-deformation resulting from the adequate Zn diffusion into grain-boundary. When the deformation was larger than 65%, the magnetic properties were deteriorated due to abnormal grain growth. In order to improve further the coercivity Hci, the samples with Dy addition were prepared. The coercivity of 12300 Oe could be obtained for anisotropic bulk Nd9.5Dy2Fe81.5Nb1B6.

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Structural and Magnetic Properties of Sm(CobalFe0.1Ni0.12Zr0.04B0.04)7.5 Melt Spun Ribbons

Materials Science Forum ◽

10.4028/www.scientific.net/msf.636-637.404 ◽

2010 ◽

Vol 636-637 ◽

pp. 404-410

Author(s):

Sofoklis S. Makridis

Keyword(s):

Magnetic Properties ◽

Hysteresis Loops ◽

Secondary Phase ◽

Maximum Energy ◽

Tem Analysis ◽

Energy Product ◽

Average Grain Size ◽

Melt Spun ◽

Melt Spun Ribbons ◽

Structural And Magnetic Properties

We have investigated the structural and magnetic properties of Sm(Co0.70Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. The arc-melted bulk samples have been used to obtain ribbons at 37 up to 55 m/sec while annealing has been performed in argon atmosphere for 30-75 min at 600-870 oC. In as-spun ribbons the hexagonal SmCo7 (TbCu7-type of structure) of crystal structure has been determined from x-ray diffraction patterns, while fcc-Co has been identified as a secondary phase. After annealing, the 1:7 phase of the as-spun ribbons transforms into 2:17 and 1:5 phases. TEM analysis shows a homogeneous nanocrystalline microstructure with average grain size of 30-80 nm. Coercivity values of 15-27 kOe are obtained from hysteresis loops traced at non-saturating fields. The coercivity decreases as temperature increases, but it is high enough to maintain values higher than 5 kOe at 380 oC. The maximum energy product at room temperature increases, as high as 7.2 MGOe, for melt-spun ribbons produced at higher wheel speed.

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Statistical Consideration of Grain Growth Mechanism of Multicrystalline Si by One-Directional Solidification Technique

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.242.35 ◽

2015 ◽

Vol 242 ◽

pp. 35-40

Author(s):

Takashi Sekiguchi ◽

Ronit R. Prakash ◽

Karolin Jiptner ◽

Xian Jia Luo ◽

Jun Chen ◽

...

Keyword(s):

Steady State ◽

Grain Boundary ◽

Directional Solidification ◽

Grain Growth ◽

Growth Mechanism ◽

Grain Shape ◽

The Other ◽

Shape Evolution ◽

Initial Stage ◽

Statistical Consideration

The grain evolution of multicrystalline Si was studied using the ingot grown from microcrystalline template. The grain shape evolution and width increase are not monotonic but may have 3 stages. On the other hand, the grain boundary (GB) analysis suggests that there exit 2 reactions, namely random GB annihilation at the initial stage and Σ3 generation and annihilation at the steady state.

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

Materials ◽

10.3390/ma14143992 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3992

Author(s):

Qingjin Ke ◽

Feilong Dai ◽

Shengxi Li ◽

Maohua Rong ◽

Qingrong Yao ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Formation ◽

High Performance ◽

Magnetic Energy ◽

Co Substitution ◽

Energy Product ◽

Melt Spun ◽

Low Costs ◽

Melt Spun Ribbons ◽

Microstructure And Magnetic Properties

Phase formation and microstructure of (Nd1-2xCexYx)14.5Fe79.3B6.2 (x = 0.05, 0.10, 0.15, 0.20, 0.25) alloys were studied experimentally. The results reveal that (Nd1-2xCexYx)14.5Fe79.3B6.2 annealed alloys show (NdCeY)2Fe14B phase with the tetragonal Nd2Fe14B-typed structure (space group P42/mnm) and rich-RE (α-Nd) phase, while (Nd1-2xCexYx)14.5Fe79.3B6.2 ribbons prepared by melt-spun technology are composed of (NdCeY)2Fe14B phase, α-Nd phase and α-Fe phase, except for the ribbon with x = 0.25, which consists of additional CeFe2 phase. On the other hand, magnetic properties of (Nd1-2xCexYx)14.5Fe79.3B6.2 melt-spun ribbons were measured by a vibrating sample magnetometer (VSM). The measured results show that the remanence (Br) and the coercivity (Hcj) of the melt-spun ribbons decrease with the increase of Ce and Y substitutions, while the maximum magnetic energy product ((BH)max) of the ribbons decreases and then increases. The tendency of magnetic properties of the ribbons could result from the co-substitution of Ce and Y for Nd in Nd2Fe14B phase and different phase constitutions. It was found that the Hcj of the ribbon with x = 0.20 is relatively high to be 9.01 kOe, while the (BH)max of the ribbon with x = 0.25 still reaches to be 9.06 MGOe. It suggests that magnetic properties of Nd-Fe-B ribbons with Ce and Y co-substitution could be tunable through alloy composition and phase formation to fabricate novel Nd-Fe-B magnets with low costs and high performance.

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Non-isothermal crystallization kinetics and hard magnetic properties of Hf1.5Zr0.5Co10FeB melt-spun ribbons

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-021-10553-4 ◽

2021 ◽

Author(s):

Nithya Christopher ◽

Kritika Anand ◽

A. K. Srivastava ◽

Nidhi Singh

Keyword(s):

Magnetic Properties ◽

Crystallization Kinetics ◽

Isothermal Crystallization ◽

Isothermal Crystallization Kinetics ◽

Melt Spun ◽

Melt Spun Ribbons ◽

Hard Magnetic Properties

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Magnetic properties of Nd60−xYxFe30Al10 (x=0,10,30) melt-spun ribbons containing two amorphous magnetic phases

Journal of Applied Physics ◽

10.1063/1.1475356 ◽

2002 ◽

Vol 91 (11) ◽

pp. 9267-9271 ◽

Cited By ~ 12

Author(s):

Z. G. Sun ◽

W. Löser ◽

J. Eckert ◽

K.-H. Müller ◽

L. Schultz

Keyword(s):

Magnetic Properties ◽

Magnetic Phases ◽

Melt Spun ◽

Melt Spun Ribbons

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Atomic ordering and magnetic properties in the Nd/sub 50/Fe/sub 40/Al/sub 10/ melt-spun ribbons

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401) ◽

10.1109/intmag.2003.1230392 ◽

2004 ◽

Author(s):

N. Lupu ◽

H. Chiriac ◽

J.M. Greneche

Keyword(s):

Magnetic Properties ◽

Atomic Ordering ◽

Melt Spun ◽

Melt Spun Ribbons

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Magnetic Properties of (Pr1−xSmx)2Fe14B Melt-Spun Ribbons

Journal of Superconductivity and Novel Magnetism ◽

10.1007/s10948-018-4645-4 ◽

2018 ◽

Vol 31 (11) ◽

pp. 3705-3710 ◽

Cited By ~ 1

Author(s):

Chengfu Xu ◽

Kanghua Chen ◽

Zhengfei Gu ◽

Guanghui Rao ◽

Gang Cheng ◽

...

Keyword(s):

Magnetic Properties ◽

Melt Spun ◽

Melt Spun Ribbons

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Influence of Co-Doping on Magnetic Properties and Magnetocaloric Effect of Fe–Co–Zr–Cu–B Melt-Spun Ribbons

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19099 ◽

2021 ◽

Vol 21 (4) ◽

pp. 2552-2557

Author(s):

Nguyen Hai Yen ◽

Nguyen Hoang Ha ◽

Pham Thi Thanh ◽

Nguyen Huy Ngoc ◽

Tran Dang Thanh ◽

...

Keyword(s):

Magnetic Properties ◽

Magnetocaloric Effect ◽

Melt Spinning ◽

Room Temperature ◽

Tangential Velocity ◽

Magnetic Behavior ◽

Entropy Change ◽

Co Doping ◽

Melt Spun ◽

Melt Spun Ribbons

In this work, we investigated magnetic properties and magnetocaloric effect in Fe90−xCoxZr7Cu1B2 (x = 0, 1, 2, 3 and 4) melt-spun ribbons. The ribbons were prepared by using a melt-spinning method with a tangential velocity of a copper wheel of 40 m·s-1. The obtained ribbons are almost amorphous. The alloys exhibit typical soft magnetic behavior with low coercivity at room temperature. A minor replacement of Fe by Co gives an increment in Curie temperature (TC) of the alloys to higher temperatures. The TC of the alloys increases from 242 to 342 K with an increase of x from 0 to 4. Maximum magnetic entropy change, ΔSm max, of the alloys, was found to be larger than 0.7 J·kg-1·K-1 in a magnetic field change ΔH of 12 kOe for all the concentrations of Co. High refrigerant capacitys (RC >100 J ·kg-1 with ΔH = 12 kOe) at room temperature region have been obtained for the alloys. The large magnetocaloric effect near room temperature suggests that the alloys can be considered as magnetic refrigerants in the range of 250–350 K.

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