Effect of Annealing on the Microstructure and Magnetic Properties of 2J4 Alloy

2016 ◽  
Vol 852 ◽  
pp. 84-89
Author(s):  
Chun Hong Li ◽  
Deng Ming Chen ◽  
Si Huang ◽  
Yi Long Ma ◽  
Jian Chun Sun ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Performance ◽  
Magnetic Energy ◽  
Domain Boundary ◽  
Magnetic Domain ◽  
Microstructural Characterization ◽  
Energy Product ◽  
Increasing Temperature ◽  
Precipitated Phases

The effect of annealing on the microstructural characterization and magnetic properties of 2J4 alloy has been investigated.The alloys were annealed in argon atmosphere for 0.5h at different temperatures.The results indicated that there were some precipitated phases afer annealing,which can pin domain boundary movement, thus leading to improved magnetic energy product and hysteresis properties due to enhanced coercivity and remanence. Magnetic domain morphology showed that the number of domains increased after heat treatment, the exchange energy between magnetic domains and the energy of magnetocrystalline anisotropy increased with increasing domain number,thus leading to better coercivity. With increasing temperature from 620°C to 680°C, saturation magnetization increased at first, and then decreased under the effect of increase in precipitates and decrease in strain and dislocations. The coercivity,hysteresis loss and ratio of the remanence to saturation magnetization keeped increasing due to increase of tiny and dispersed precipitates. This study can provide theoretically a reliable way for preparing 2J4 magnetic alloys with high performance.

scholarly journals Development of a High-Performance-Ferrite Magnet Fabrication Process without Sintering Additives

2021 ◽  
Vol 59 (8) ◽  
pp. 551-559
Author(s):  
Pyeong-Yeol Yu ◽  
Min-Ho Kim ◽  
Young-Min Kang
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Performance ◽  
Secondary Phase ◽  
Batch Process ◽  
Maximum Energy ◽  
Magnetic Flux Density ◽  
Sintering Additives ◽  
Energy Product ◽  
Hard Magnetic Properties

Sintered M-type hexaferrites with the chemical formula of Sr0.3Ca0.4La0.3Fe9.8Co0.2-xMnxSi0.135O19-d (x = 0, 0.05, 0.1, 0.2) and Sr0.3Ca0.4La0.3Fe9.8-yCo0.2MnySi0.135O19-d (y = 0.05, 0.1, 0.2) were prepared by conventional solid station reaction routes. A high sintering density of more than 95% of the theoretical density was achieved in all hexaferrite samples when calcination was carried out at 1100 oC for 4 h, followed by sintering at 1230-1250 oC for 2 h without the use of sintering additives. High saturation magnetization and coercivity were achieved simultaneously at the x = 0.05 composition, where Mn replaces part of the Co. The secondary phase Fe2O3 generated by the initial addition of SiO2 was gradually reduced when the Fe contented was decreased in the Sr0.3Ca0.4La0.3Fe9.8-zCo0.15Mn0.05Si0.135O19-d samples, and a single M-type hexaferrite phase was confirmed in the Sr0.3Ca0.4La0.3Fe8.3Co0.15Mn0.05Si0.135O19-d (z = 1.5) sample, which also exhibited optimized hard magnetic properties, with a saturation magnetization of 4581 G and coercivity of 4771 Oe. Anisotropic sintered magnets were fabricated using the optimized composition, and showed excellent hard magnetic properties, with a remanent magnetic flux density of 4400 G and intrinsic coercivity of 4118 Oe, and a maximum energy product of 4.72 M·G·Oe. This result is very promising because high magnet performance can be achieved with a single batch process without the need for sintering additives during the process.

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

Materials ◽  
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.

Microstructure and Magnetic Properties of Hot-Pressed and Hot-Deformed Composite Magnets Produced by Spark Plasma Sintering Method

2011 ◽  
Vol 686 ◽  
pp. 740-744 ◽  
Author(s):  
Yi Long Ma ◽  
Deng Ming Chen ◽  
Qian Shen ◽  
Peng Jun Cao
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Hot Pressing ◽  
Magnetic Energy ◽  
Pressing Temperature ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Products ◽  
Fe Addition

Bulk isotropic and anisotropic Nd13.5Fe80.4Ga0.5B5.6 and Nd13.5Fe80.4Ga0.5B5.6/Fe magnets were synthesized by applying spark plasma sintering (SPS) technique. The effect of hot-pressing temperature on the magnetic properties of hot-pressed (HP) and hot-deformed (HD) magnets without additive and with 5% Fe addition was investigated. With increasing sintering temperature for HP magnets, the grain grew gradually. For HD magnets, the optimal magnetic properties could be obtained at hot-pressing temperature 680°C due to the development of desired c-axis texture and uniform microstructure, which resulted from the appropriate and uniform grain size in HP magnets. Fe addition could enhance remanence (Br) and magnetic energy products ((BH)m) of HP and HD magnets. However, the maximum magnetic energy product of HD magnets decreased when hot-pressing temperature was higher than 650°C.

Effect of (Sm,Pr)2Co7 phase on magnetic properties of high-performance (Sm,Pr)Co5 magnet based on EBSD analysis and magnetic domain observation

2021 ◽  
Vol 181 ◽  
pp. 111478
Author(s):  
Jianjun Yang ◽  
Dongtao Zhang ◽  
Rongchun Zhu ◽  
Xiaochang Xu ◽  
Dan Wu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
High Performance ◽  
Magnetic Domain ◽  
Ebsd Analysis

Magnetic properties prediction of NdFeB magnets by using support vector regression

2014 ◽  
Vol 28 (23) ◽  
pp. 1450177
Author(s):  
Wende Cheng
Keyword(s):  
Magnetic Properties ◽  
Support Vector Regression ◽  
Magnetic Energy ◽  
Practical Method ◽  
Percentage Error ◽  
Support Vector ◽  
Ndfeb Magnets ◽  
Energy Product ◽  
Experimental Process ◽  
Leave One Out

A novel model using support vector regression (SVR) combined with particle swarm optimization (PSO) was employed to construct mathematical model for prediction of the magnetic properties of the NdFeB magnets. The leave-one-out cross-validation (LOOCV) test results strongly supports that the generalization ability of SVR is high enough. Predicted results show that the mean absolute percentage error for magnetic remanence Br, coercivity Hcj and maximum magnetic energy product (BH) max are 0.53%, 3.90%, 1.73%, and the correlation coefficient (R2) is as high as 0.839, 0.967 and 0.940, respectively. This investigation suggests that the PSO-SVR is not only an effective and practical method to simulate the properties of NdFeB , but also a powerful tool to optimatize designing or controlling the experimental process.

Fabrication of NdFeB Thin Film and Its Application in MEMS

2002 ◽  
Author(s):  
Pan Zheng ◽  
Mohammad Kilani ◽  
Yousef S. Haik ◽  
Ching-Jen Chen
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Thin Films ◽  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Transmission System ◽  
Gear Transmission ◽  
Energy Product ◽  
Gear Transmission System ◽  
Residual Inductance

The paper measures the magnetic properties of NdFeB thin films developed under the effects of magnetic field. The samples exhibited a larger residual inductance, saturation magnetization and energy product than those treated without field or with weaker field. Magnetic MEMS was introduced with application of the NdFeB film to micro device such as pumps and gear transmission system.

Magnetic Domain Structure of Nanocrystalline Zr18-xHfxCo82 Ribbons: Effect of Hf

2013 ◽  
Vol 1557 ◽  
Author(s):  
Lanping Yue ◽  
I. A. Al-Omari ◽  
Wenyong Zhang ◽  
Ralph Skomski ◽  
D. J. Sellmyer
Keyword(s):  
Magnetic Properties ◽  
Domain Structure ◽  
Structure Refinement ◽  
Magnetic Domain ◽  
Maximum Energy ◽  
Magnetic Domain Structure ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Domain Structures ◽  
Rapidly Solidified

ABSTRACTThe effect of Hf on the permanent magnetism of nanocrystalline Zr18-xHfxCo82 ribbons (x = 0, 2, 4, and 6) was investigated by magnetic properties measurement and magnetic force microscopy (MFM). Emphasis is on the local magnetic domain structures in polycrystalline rapidly solidified Zr18-xHfxCo82 ribbons for four different samples with small fractions of Hf dopants (x ≤ 6). The investigation of the magnetic properties of the Zr18-xHfxCo82 ribbons revealed that all the samples under investigation are ferromagnetic at room temperature, and the corresponding MFM images show bright and dark contrast patterns with up-down magnetic domain structures. It is found that the saturation magnetization and the coercivity depend on Hf doping concentration x in the samples. For a sample with Hf concentration x = 4, the maximum energy product (BH)max value is 3.7 MGOe. The short magnetic correlation length of 131 nm and smallest root-mean-square phase shift value of 0.680 were observed for x = 4, which suggests the refinement of the magnetic domain structure due to weak intergranular exchange coupling in this sample. The above results indicate that suitable Hf addition is helpful for the magnetic domain structure refinement, the coecivity enhancement, and the energy-product improvement of this class of rare-earth-free nanocrystalline permanent-magnet materials.

Effects of preparation processes on structure and magnetic properties of Nd2Fe14B/α–Fe-type nanocomposite magnets

2001 ◽  
Vol 16 (3) ◽  
pp. 709-715 ◽  
Author(s):  
Bao-zhi Cui ◽  
X. K. Sun ◽  
L. Y. Xiong ◽  
Wei Liu ◽  
Zhi-dong Zhang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Magnetic Energy ◽  
Homogeneous Distribution ◽  
Grain Sizes ◽  
Energy Product ◽  
Nanocomposite Magnets ◽  
Intrinsic Coercivity

The structure and magnetic properties of Nd8.4Fe86Mo1.1B4.5 nanostructured magnets prepared by mechanical alloying (MA), compared with those by mechanical milling (MM), were studied. The intrinsic coercivity μ0Hc, the reduced remanence Jr/Js, and the maximum magnetic energy product (BH)max for Nd8.4Fe86Mo1.1B4.5 magnets were prepared by MM were notably higher than the values of the corresponding MA-prepared samples. The average grain sizes of both α–Fe and Nd2Fe14B in the MM-prepared samples were measurably smaller than corresponding values of the MA-prepared samples. A more homogeneous distribution of α–Fe grains in the MM-prepared samples than in the MA-prepared samples was obtained.

scholarly journals Enhanced Magnetization of Sol-Gel Synthesized Pb-Doped Strontium Hexaferrites Nanocrystallites at Low Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Shahid M. Ramay ◽  
Shahid Atiq ◽  
Murtaza Saleem ◽  
Asif Mahmood ◽  
Saadat A. Siddiqi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Saturation Magnetization ◽  
Structural Parameters ◽  
Hexagonal Phase ◽  
Magnetic Moments ◽  
Sol Gel ◽  
Magnetic Characteristics ◽  
Energy Product ◽  
Pb Substitution

Effect of Pb doping on the structural and low temperature magnetic properties ofSrPbxFe12-xO19(x=0,0.1,0.2,0.3,and  0.4), synthesized by sol-gel autocombustion technique, has been investigated. The powder samples were sintered at 800°C for 2 h in order to develop the stable hexagonal phase, characteristic of the SrFe12O19structure. The consequences of Pb substitution (at iron sites) on various structural parameters like lattice constants, unit cell volume, crystallite size, and porosity have been discussed. Fourier transform infrared frequency bands were utilized to determine the formation of tetrahedral and octahedral clusters of M-type ferrites. Hexagonal texture of the grains, a characteristic of the hexagonal crystal structure of SrFe12O19, was refined by Pb substitution. The magnetic properties, determined using a vibrating sample magnetometer, revealed that saturation magnetization decreased, while coercivity was increased with the increase of Pb contents. However, the increased squareness ratio and hence the energy product motivate the utilization of these ferrite compositions where hard magnetic characteristics are required. The increased values of saturation magnetization were observed at reduced temperature of 200 K, attributable to the better spin alignments of individual magnetic moments at low temperature.

Effect of Boron Addition on Magnetic-Domain Structure of Rapidly Quenched Zr2Co11−Based Nanomaterials

MRS Advances ◽  
2016 ◽  
Vol 1 (34) ◽  
pp. 2379-2385 ◽  
Author(s):  
Lanping Yue ◽  
Yunlong Jin ◽  
David J. Sellmyer
Keyword(s):  
Magnetic Properties ◽  
Domain Structure ◽  
Structure Refinement ◽  
Magnetic Domain ◽  
Domain Size ◽  
Maximum Energy ◽  
Magnetic Domain Structure ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Domain Structures

ABSTRACTThe boron-content dependence of magnetic domain structures and magnetic properties of nanocrystalline Zr16Co82.5−xMo1.5Bx (x = 0, 1, 2, 3, 4) melt-spun ribbons have been investigated. Compared to x = 0, the smaller average domain size with a relatively short magnetic correlation length of 120 nm and largest root-mean-square phase shift value of 0.94° are observed for x = 1. The best magnetic properties of coercivity Hc = 5.4 kOe, maximum energy product (BH)max = 4.1 MGOe, and saturation polarization Js = 7.8 kG, were obtained for the ribbon with x = 1. The optimal B addition enhances the content of hard magnetic phase, promotes magnetic domain structure refinement, and increases the surface roughness, results in the enhancement of magnetic anisotropy, and thus leads to a significant increase in coercivity and energy product in this sample.

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