Misch-Metal and/or Aluminum Substitutions in ND-FE-B Permanent Magnets

ABSTRACTThe effects of misch-metal–and/or Al substitutions in the Nd-Fe-B alloy system have been investigated. Selected compositions were processed into magnets using the conventional powder metallurgy technique. As expected, misch-metal substitutions act to degrade the intrinsic magnetic characteristics and thus degrade the properties of the sintered magnet. It was observed that at a level of 25% of the total rare earth being comprised of misch-metal, energy products of the order of 25 MGOe were still able to be achieved. Processing of such material is difficult because higher sintering temperatures are required to fully densify the magnet, and the grain growth that occurs at these temperatures dramatically reduces the coercivity. The effects of misch-metal substitutions are quantified in this discussion.Al was found to be beneficial for improving the coercivity in both the Nd-Fe-B and misch-metal-Fe-B alloy systems. Unfortunately Al substitutions reduce both the remanence and the Curie temperature. If the Al content is kept to 1 wt.% or less, magnets exhibiting reasonable properties can be made. Al doping as opposed to doping with expensive heavy rare earth elements such as Th or Dy is a less costly method of improving Hei, in the Nd-Fe-B magnets.

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Bio-compatible Thin Films on Rare Earth Based Permanent Magnets

MRS Proceedings ◽

10.1557/proc-697-p5.25 ◽

2001 ◽

Vol 697 ◽

Author(s):

Ecaterina Vasilescu ◽

Paula Drob ◽

Doina Raducanu ◽

Lucia Angelescu ◽

Constantin Iliuc

Keyword(s):

Rare Earth ◽

Permanent Magnets ◽

Wear Behavior ◽

Artificial Saliva ◽

Dental Materials ◽

Localized Corrosion ◽

Chemical Compositions ◽

Prosthetic Devices ◽

Al Content ◽

The Stability

AbstractThe item of the paper is focussed on some bio-compatible coatings for rare earth based permanent magnets, which are used as dental materials for prosthetic devices as retention units. The studied alloy belongs to Nd-Fe-B system with some Dy and Al content. The double-layer coatings had different chemical compositions; first layer: Ag30-Cr70, Co30-Cr70, Stainless Steel and the second layer: titanium nitride (TiN). Data about corrosion behavior, wear resistance and adhesion are presented. The corrosion resistance of these coatings was tested in artificial saliva, using electrochemical potentiostatic and potentiodynamic polarization techniques. The stability in the corrosion media, the localized corrosion susceptibility and the corrosion rates were determined. It resulted that the Nd30-Dy5-Fe-Al0.4-B alloy with Ag30-Cr70 + TiN film is very stable in artificial saliva. The wear behavior of the coatings in different conditions of contact and load was tested, also. The adhesion was determined by scratching test.

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Hydrogenation of Nd-Fe Alloys under Conditions of Different Pressure and Hydrogen Concentration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.683.44 ◽

2016 ◽

Vol 683 ◽

pp. 44-52 ◽

Cited By ~ 2

Author(s):

Aleksander Buinovskiy ◽

Vladimir Sofronov ◽

Evgenii Kartashov ◽

Mikhail Kalaev

Keyword(s):

Rare Earth ◽

Surface Area ◽

Permanent Magnets ◽

Solid Phase ◽

High Strength ◽

Magnetic Characteristics ◽

Hydrogenation Rate ◽

Mechanical Grinding ◽

Fe Alloys ◽

Process Scale

The paper presents the research results of the process of hydride grinding of Nd-Fe alloys, which are used for solid-phase alloying of base magnetic alloys having Nd-Fe-B system in order to improve magnetic characteristics of rare-earth permanent magnets. Alloys having rare-earth metals including Nd-Fe can be produced with the help of the out-of-furnace fluoride technology designed by the authors of this article. Hydrogenation of Nd-Fe alloys is used at the stage of their grinding. It is determined by complexity of mechanical grinding of these alloys because of their tensility and high strength. The thermodynamics of the process of alloy hydrogenation is considered. The effects of hydrogen surplus, the process scale and the surface area of alloys on their hydrogenation rate are investigated. The paper also presents the results of metallographic and roentgen-phase analyses of the sample surfaces of alloys which were hydrogenated. The analysis of the specific surface area of the materials is given.

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In vitro safety evaluation of rare earth-lean alloys for permanent magnets manufacturing

Scientific Reports ◽

10.1038/s41598-021-91890-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Carlos Rumbo ◽

Cristina Cancho Espina ◽

Jürgen Gassmann ◽

Olivier Tosoni ◽

Rocío Barros García ◽

...

Keyword(s):

Rare Earth ◽

Permanent Magnets ◽

Vibrio Fischeri ◽

Model Organisms ◽

In Vitro Assays ◽

Lower Percentage ◽

Magnetic Characteristics ◽

Toxicological Evaluation ◽

The Impact

AbstractDue to their exceptional physico-chemical and magnetic characteristics, rare earth (RE) permanent magnets are applied in multiple critical technologies. However, several environmental and economic difficulties arising from obtaining RE elements have prompted the search of alternatives with acceptable magnetic properties but containing a lower percentage of these elements in their composition. The aim of this work was to perform a preliminary toxicological evaluation of three forms of newly developed RE-lean alloys (one NdFeTi and two NdFeSi alloys) applying different in vitro assays, using as a benchmark a commercial NdFeB alloy. Thus, the effects of the direct exposure to powder suspensions and to their derived leachates were analysed in two model organisms (the A549 human cell line and the yeast Saccharomyces cerevisiae) applying both viability and oxidative stress assays. Moreover, the impact of the alloy leachates on the bioluminescence of Vibrio fischeri was also investigated. The obtained data showed that only the direct interaction of the alloys particulates with the applied organisms resulted in harmful effects, having all the alloys a comparable toxicological potential to that presented by the reference material in the conditions tested. Altogether, this study provides new insights about the safety of NdFeTi and NdFeSi alloys.

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L10 rare-earth-free permanent magnets: The effects of twinning versus dislocations in Mn-Al magnets

Physical Review Materials ◽

10.1103/physrevmaterials.4.094402 ◽

2020 ◽

Vol 4 (9) ◽

Author(s):

Yuxiao Jia ◽

Yuye Wu ◽

Shuang Zhao ◽

Shulan Zuo ◽

Konstantin P. Skokov ◽

...

Keyword(s):

Rare Earth ◽

Permanent Magnets

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Temperature-dependent magnetocrystalline anisotropy of rare earth/transition metal permanent magnets from first principles: The light RCo5 (R=Y, La-Gd) intermetallics

Physical Review Materials ◽

10.1103/physrevmaterials.3.101401 ◽

2019 ◽

Vol 3 (10) ◽

Cited By ~ 11

Author(s):

Christopher E. Patrick ◽

Julie B. Staunton

Keyword(s):

Rare Earth ◽

Transition Metal ◽

First Principles ◽

Permanent Magnets ◽

Magnetocrystalline Anisotropy ◽

Temperature Dependent

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Special Issue: Advances in Computational Electromagnetics

Magnetochemistry ◽

10.3390/magnetochemistry7060089 ◽

2021 ◽

Vol 7 (6) ◽

pp. 89

Author(s):

Valerio De Santis

Keyword(s):

Rare Earth ◽

Magnetic Materials ◽

Permanent Magnets ◽

Computational Electromagnetics ◽

Superconducting Materials ◽

Special Issue ◽

Full Characterization ◽

Recent Advances

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...]

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Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

npj Quantum Materials ◽

10.1038/s41535-020-00301-6 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Anna Galler ◽

Semih Ener ◽

Fernando Maccari ◽

Imants Dirba ◽

Konstantin P. Skokov ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Magnetic Anisotropy ◽

High Performance ◽

Kondo Effect ◽

Quantitative Description ◽

Many Body ◽

Heavy Rare Earth Elements ◽

Fe Intermetallics ◽

Full Temperature

AbstractCerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce–Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials suppressing the Ce-4f contribution to the magnetic anisotropy, in striking contrast to the effect of nitrogenation in isostructural intermetallics containing other rare-earth elements. We determine the full temperature dependence of the Ce-4f single-ion anisotropy and show that even unscreened Ce-4f moments contribute little to the room-temperature intrinsic magnetic hardness. Our study thus establishes fundamental constraints on the potential of cerium-based permanent magnet intermetallics.

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Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

Applied Sciences ◽

10.3390/app11073102 ◽

2021 ◽

Vol 11 (7) ◽

pp. 3102

Author(s):

Md. Zakirul Islam ◽

Seungdeog Choi ◽

Malik E. Elbuluk ◽

Sai Sudheer Reddy Bonthu ◽

Akm Arafat ◽

...

Keyword(s):

Rare Earth ◽

Permanent Magnets ◽

Design Procedure ◽

Lumped Parameter Model ◽

High Power Density ◽

Analytical Design ◽

Synchronous Reluctance Motor ◽

Lumped Parameter ◽

Reluctance Motor ◽

External Rotor

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

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