A Comparative Study between Low and High-Energy Milling Processes for the Production of HD PrFeCoBNb Sintered Magnets

2008 ◽  
Vol 591-593 ◽  
pp. 114-119 ◽  
Author(s):  
E.A. Périgo ◽  
E.P. Soares ◽  
Hidetoshi Takiishi ◽  
C.C. Motta ◽  
Rubens Nunes de Faria Jr.
Keyword(s):  
Ball Milling ◽  
Permanent Magnets ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
High Energy Milling ◽  
Energy Product ◽  
Energy Processing ◽  
Hydrogen Decrepitation ◽  
High Degree

Roller-ball milling (RBM) or planetary ball milling (PBM) have been used together with the hydrogen decrepitation (HD) process to produce sintered permanent magnets based on a mixture of Pr16Fe76B8 and Pr14.00Fe63.90Co16.00B6.00Nb0.10 magnetic alloys. Five distinct compositions have been studied comparing low- and high-energy milling. Magnets with a particular composition and prepared using these two routes exhibited similar magnetic properties. Modifications have been carried out in the procedure of the HD stage for PBM in order to guarantee a high degree of crystallographic alignment. Pr15.00Fe69.95Co8.00B7.00Nb0.05 magnets showed the best maximum energy product for both processing routes (~ 247 kJm-3). A significant reduction in the milling time (93%) has been achieved with high-energy processing, the greatest advantage over the low-energy route.

NdFeB/αFe Nanocomposite Permanent Magnets with Enhanced Properties Prepared by Spark Plasma Sintering

2011 ◽  
Vol 672 ◽  
pp. 229-232
Author(s):  
Marian Grigoraş ◽  
M. Lostun ◽  
Nicoleta Lupu ◽  
Horia Chiriac
Keyword(s):  
Spark Plasma Sintering ◽  
Permanent Magnets ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Melt Spun Ribbons

Nanocomposite NdFeB/αFe magnets were obtained by spark plasma sintering technique using high energy ball-milled Nd-Fe-B melt-spun ribbons mixed in different weight ratios with Fe commercial powders. The remanence of SPS nanocomposite magnets increases with the Fe powders content from 6.1 for 4 wt.% Fe to 6.4 kG for 5 wt.% Fe, while the estimated maximum energy product is also increased from 9.0 to 10.6 MGOe.

Influence of Alloying Elements Zr, Nb and Mo on the Microstructure and Magnetic Properties of Sintered Pr-Fe-Co-B Based Permanent Magnets

2018 ◽  
Vol 930 ◽  
pp. 440-444
Author(s):  
Melissa Rohrig Martins da Silva ◽  
R.G.T. Fim ◽  
S.C. Silva ◽  
Julio Cesar Serafim Casini ◽  
P.A.P. Wendhausen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Alloying Elements ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Cast Alloys ◽  
Hydrogen Decrepitation ◽  
Microstructure And Magnetic Properties

The addition of alloying elements on rare-earth permanent magnets is one of the methods used to improve the magnetic properties. This present work evaluates the influence of alloying elements such as Zr, Nb and Mo on the microstructure and magnetic properties of sintered Pr-FeCo-B based permanent magnets. The permanent magnets were produced by the conventional powder metallurgy route using powder obtained by hydrogen-decrepitation (HD) method from as cast alloys. In order to produce the magnet Pr16Fe66,9Co10,7B5,7Cu0,7 without alloying elements the mixture of alloys method was employed, mixing two compositions: Pr20Fe73B5Cu2 (33% w.t) and Pr14Fe64Co16B6 (67% w.t). With the purpose of evaluating the influence of the alloying elements, the Pr14Fe64Co16B6X0,1 (where X= Zr, Nb or Mo) (67% w.t) alloy was employed. The characterization of the alloys and the magnets was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and the magnetic properties were measured using a permeameter. The magnet without any additions presented the highest intrinsic coercivity (μ0iHc = 748 KA.m-1) while the magnet with Nb addition presented higher remanence (Br = 1,04 T). The magnet with Zr addition presented the highest maximum energy product (BHmáx = 144 KJ.m-3), and the magnet with Mo addition showed the highest squareness factor (SF = 0,73).

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

Bulk Nanocrystalline Permanent Magnets by Selective Laser Melting

2021 ◽  
Vol 58 (10) ◽  
pp. 630-643
Author(s):  
F. Trauter ◽  
J. Schanz ◽  
H. Riegel ◽  
T. Bernthaler ◽  
D. Goll ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Field Strength ◽  
Selective Laser Melting ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Laser Melting ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Bulk Nanocrystalline ◽  
Micrometer Scale

Abstract Fe-Nd-B powders were processed by additive manufacturing using laboratory scale selective laser melting to produce bulk nanocrystalline permanent magnets. The manufacturing process was carried out in a specially developed process chamber under Ar atmosphere. This resulted in novel types of microstructures with micrometer scale clusters of nanocrystalline hard magnetic grains. Owing to this microstructure, a maximum coercive field strength (coercivity) μ0Hc of 1.16 T, a remanence Jr of 0.58 T, and a maximum energy product (BH)max of 62.3 kJ/mm3could, for example, be obtained for the composition Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8.

Microstructure Of Fe-Nd-B Alloys Tailored To Approach Theoretical Coercrvtty Limits

1999 ◽  
Vol 5 (S2) ◽  
pp. 26-27
Author(s):  
Kannan M. Krishnan ◽  
Er. Girt ◽  
E. C. Nelson ◽  
G. Thomas ◽  
Ferdinand Hofer
Keyword(s):  
Magnetic Particles ◽  
Permanent Magnets ◽  
Spontaneous Magnetization ◽  
Particle Interaction ◽  
Maximum Energy ◽  
Interacting Particles ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Oriented Samples ◽  
The Difference

Performance of permanent magnets for a variety of applications is often determined by the maximum energy product (BH)max. In order to obtain high (BH)max permanent magnetic materials have to have large coercivity. In theory the coercive field of ideally oriented, non-interacting, single domain, magnetic particles, assuming Kl is much bigger than K2, was shown to be He = 2K1/Ms - N Ms, where Kl and K2 are the magnetocrystalline anisotropy constants, Ms is the spontaneous magnetization and N is the demagnetization factor. For randomly oriented non-interacting particles the Stoner-Wohlfarth model predicts that the value of Hc decreases to about half. However, experimentally obtained values of the coercitive fields in permanent magnets are 3 to 10 and 2 times smaller for well oriented and randomly oriented samples, respectively. This discrepancy was attributed to inter-particle interaction and the microstructure of the permanent magnets. In order to understand the difference between the theoretically predicted and experimentally obtained results for He we prepared rapidly quenched, Nd-rich, NdxFe14B (2 < x < 150) ribbons.

scholarly journals Additive Manufacturing of Anisotropic Sm-Fe-N Nylon Bonded Permanent Magnets

2021 ◽  
Author(s):  
Kinjal Gandha ◽  
Mariappan Paranthaman ◽  
Brian Sales ◽  
Haobo Wang ◽  
Adrian Dalagan ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Magnetic Particles ◽  
Permanent Magnets ◽  
Cost Effective ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Polyamide 12 ◽  
Energy Technologies ◽  
Energy Product ◽  
Bonded Magnet

Fabricating a bonded magnet with a near-net shape in suitable thermoplastic polymer binders is of paramount importance in the development of cost-effective energy technologies. In this work, anisotropic Sm2Fe17N3 (Sm-Fe-N) bonded magnets are additively printed using Sm-Fe-N anisotropic magnetic particles in a polymeric binder polyamide-12 (PA12). The anisotropic bonded permanent magnets are fabricated by Big Area Additive Manufacturing followed by post-aligned in a magnetic field. Optimal post-alignment results in an enhanced remanence of ~ 0.68 T in PA12 reflected in a parallel-oriented (aligned) measured direction. The maximum energy product achieved for the additively printed anisotropic bonded magnet of Sm-Fe-N in PA12 polymer is 78.8 KJ m-3. Our results show advanced processing flexibility of additive manufacturing for the development of Sm-Fe-N bonded magnets in polymer media designed for applications with no critical rare earth magnets.

Influence of Milling Time on Magnetic Properties and Microstructure of Sintered Nd-Fe-B Based Permanent Magnets

2018 ◽  
Vol 930 ◽  
pp. 445-448
Author(s):  
R.G.T. Fim ◽  
M.R.M. Silva ◽  
S.C. Silva ◽  
Julio Cesar Serafim Casini ◽  
P.A.P. Wendhausen ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Permanent Magnets ◽  
Milling Time ◽  
Maximum Energy ◽  
Inhomogeneous Distribution ◽  
Maximum Energy Product ◽  
Grain Sizes ◽  
Energy Product

In this paper, the effect of the grain size on sintered Nd-Fe-B based permanent magnets was investigated. In order, the magnets were produced by different milling times at 200 rpm and then vacuum sintered at 1373 K for 60 minutes followed by cooling outside the furnace. The magnets either produced by lower and higher milling times (30 and 75 minutes) exhibited lower remanence and coercivity, due the inhomogeneous distribution of the grain sizes. The magnet produced by intermediary milling time (45 minutes) exhibited the highest properties among all samples, with remanence of 1.06 T, coercivity of 891.3 KA.m-1, maximum energy product of 211 KJ.m3and a squareness factor equal 0.92.

Study on the Nanostructure and Magnetic Properties of NdFeNbB Permanent Magnets

2010 ◽  
Vol 638-642 ◽  
pp. 1749-1754
Author(s):  
X.F. Wang ◽  
X.Y. Chen ◽  
Z.L. Jiang ◽  
Y. Chen ◽  
H.M. Chen
Keyword(s):  
Exchange Coupling ◽  
Permanent Magnets ◽  
Coupling Effect ◽  
Maximum Energy ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Maximum ◽  
Intrinsic Coercivity

Nd2Fe14B/-Fe nanocomposite permanent magnet contains the hard and soft magnetic phases, Nd2Fe14B and -Fe respectively. An exchange coupling effect exists between the two magnetic phases. The effect of alloying element Nb on its nanostructure and properties have been studied. Adding Nb to the alloy is effective to refine grains, a relatively small grain size causes a high intrinsic coercivity, remanence and therefore a high maximum energy product, (BH)max. MFM (Magnetic Force Microscope) was used to observe the magnetic micro-domain structure in the nanophase alloys. The length of the magnetic contrast shows a significant dependence on the microstructure and phase constitution, and the longer length is correspond with the larger exchange coupling effect between the soft and hard magnetic phases.

Magnetic Silicone Rubbers

1983 ◽  
Vol 56 (2) ◽  
pp. 322-326 ◽  
Author(s):  
Petra Štefcová ◽  
Miroslav Schatz
Keyword(s):  
Magnetic Properties ◽  
Coercive Force ◽  
Silicone Rubber ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Silicone Rubbers

Abstract The method of preparation of elastic permanent magnets of silicone rubber is described, and the values of the basic magnetic properties of these rubbers, i.e., the coercive force, the remanent induction, and the maximum energy product, are given.

Microstructure of high-energy product Fe-Nd-B magnequench ribbons

1986 ◽  
Vol 44 ◽  
pp. 826-827
Author(s):  
Y. L. Chen
Keyword(s):  
Anisotropy Field ◽  
Microstructural Characterization ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Anisotropy ◽  
Energy Products ◽  
Very High

Melt-spun Fe-Nd-B MAGNEQUENCH® ribbons have been produced by Croat et al. with energy products in excess of 10 MG.Oe using a relatively narrow window of composition and quenching speed. The hard magnetic phase has subsequently been identified as the Nd2Fe14B compound which has a very high anisotropy field. The microstructure of the MAGNEQUENCH® ribbon which has a maximum energy product of 14.1 MG•0e was found to consist of equiaxed Nd2Fe14B grains surrounded by a very thin intergranular film. This paper presents the results of some of our earlv work on the microstructural characterization of high energy product MAGNEQUENCH® ribbons having nominal compositions of Nd13Fe82.6B4.4 and Nd15Fe79.9B5.1. The purpose of this investigation was to characterize the microstructures of various MAGNEQUENCH® ribbons for correlation with their magnetic properties.

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