United States

Sm-Co hard magnetic compound has attractive intrinsic properties of high anisotropy field and high Curie temperature. To develop high coercivity and high magnetization anisotropic magnets for high temperature environmental applications based on the Sm-Co compound, achieving a high coercivity in monocrystalline powder is necessary. It is well known that the coercivity of monocrystalline powder strongly depends on the particle size. As a new process, we focused on the induction thermal plasma (ITP) process as a physical bottom up process which enables us to prepare nanopowder with single crystalline. In this work, we explored the potential and the possibility to apply this ITP process to prepare Sm-Co alloy nanopowder.
We used two powders of the mixture of Sm and Co metal powder with an atomic ratio of Sm:Co = 1:5 and SmCo5 alloy powder as raw material and tried to identify the obtained phases through this alloying process. The processed nanopowders from mixed powder and alloy powder were denoted as S1 and S2, respectively.
The SEM images show that the particle shape was nonangular. The mean particle sizes of the S1 and S2 were estimated to be 61 nm and 31 nm, respectively. According to the XRD profile, magnetic alloy phases of SmCo5 and Sm2Co17 were obtained for both S1 and S2. Therefore, we successfully prepared the Sm-Co alloy fine particles by the ITP process. The maximum coercivity of 5.6 kOe was achieved for S1, although the large amount of the soft magnetic phase of Co was also found in the XRD profile. By controlling the alloying process actively, such as temperature distribution in the chamber, cooling rate and powder feed rate, much higher coercivity can be expected when the only Sm-Co hard magnetic phases were obtained through the ITP process.

REPM 2021: The 26th International Workshop on Rare-Earth and Future Permanent Magnets and their Applications

Sm-Co hard magnetic alloy nanopowder prepared by induction thermal plasma process

sm-co

induction thermal plasma

magnetic nanoparticles

It is our great pleasure to invite you to attend the 26th International Workshop on Rare Earth and Future Permanent Magnets and Their Applications (REPM2021) which will be held virtually on June 7-10, 2021. Please note, this is an updated schedule due to COVID-19 travel restrictions which forced us to postpone the conference from summer of 2020. The REPM workshop takes place every two years and is the premier conference on permanent magnets covering a wide range of topics including:

* Rare earth magnets
* Rare earth-free magnets
* Raw materials, mining and recycling
* Advanced synthesis, processing and characterization techniques
* Theoretical modeling of coercivity
* Fundamental properties of advanced magnetic materials
* Thin film magnets
* Applications of permanent magnets

***Workshop***
The workshop will be chaired by Professor George C. Hadjipanayis, University of Delaware, Newark, DE and Dr. Jinfang Liu, President & COO of Electron Energy Corporation, Landisville, PA.
The objectives of the workshop are to bring together engineers and scientists who work on permanent magnets and their applications to present their latest results and exchange ideas on a wide range of relevant topics including resources, raw materials, recycling, processing, fundamental and hard magnetic properties and applications of rare earth and future magnets.

To regsiter for this event, please follow the link below.

poster

Sm-Fe-N is one of prospective candidates for new generation permanent magnet materials due to its extremely high anisotropy field as well as a quite high Curie temperature. A serious drawback of this material is that sintering at temperatures above 620C results in thermal decomposition, making impossible to produce bulk specimens by conventional powder metallurgical processes. Previously, our research group employed pressure current sintering and succeeded in producing isotropic bulk Sm-Fe-N magnets. However, it was also revealed that the coercivity of the original powder was significantly degraded by sintering. In the later study we proposed a hypothesis that the surface oxide might be reduced to form alpha-Fe during sintering. Our most recent study actually proved this hypothesis. To overcome this problem, our group recently developed a low-oxygen powder metallurgy technique wherein all the powder metallurgical processes are carried out inside glove boxes. This technique enabled us to produce extremely high performance Sm-Fe-N fine powder, making it possible to produce anisotropic bulk magnet without coercivity degradation due to the reduction of oxide. 
Nevertheless, another newly arisen problem is the maximum energy product of the sintered anisotropic magnet is not as great as that of the aligned original powder although the high coercivity is maintained. It is quite possible that the particles are damaged during the pulverization process. In this study, the crystallinity and the microstructure of the Sm-Fe-N powder produced by our low oxygen powder metallurgical process.
Commercially available Sm-Fe-N powder was subjected to pulverization by jet-milling with nitrogen gas inside a glove box. The obtained fine powder was gently oxidized at a pass box and then taken out to outside glove box. X-ray diffraction (XRD) was performed to check the crystallinity of the powder. The fine powder was then brought inside a vacuum chamber of focused ion beam – scanning electron microscope (FIB-SEM) apparatus to pick up microsample for transmission electron microscopy (TEM) observation. The microsample was picked up so that the microstructure of the whole particle can be visualized. The TEM observation was carried out using FEI Talos operated at 200 kV. The magnetic properties were measured by using physical property measurement system equipped with vibrating sample magneto meter (PPMS-VSM, Quantum Design/ Dynacool 7).
The particle diameters were significantly reduced down to submicron region, and the coercivity was significantly increased consequently. The maximum energy product of the aligned powder exhibited 43 MGOe in a good case. However, careful analyses of the XRD patterns of those as-milled powders revealed that the full width half maxima (FWHM) significantly increased after jet-milling. Also, the TEM observation revealed that there are polycrystalline regions at the surfaces of pulverized particles. It is likely that these polycrystalline regions are the critical factor of the deterioration of the magnet properties after. During the talk, a possible strategy to improve the performance of the sintered magnets will be discussed.


Roles of local texture in crystallinity and magnetic properties of highly coercive Sm-Fe-N fine powder by jet-milling

The rapid development of green technologies like electric vehicles has spurred 
burgeoning interest in searching for new permanent magnetic materials which could 
be utilized as motors and generators. SmFe12-based compounds, one of the most 
promising candidates of next-generation permanent magnets from the ThMn12-structure family, exhibit excellent intrinsic hard magnetic properties such as high saturation magnetization, large anisotropic field, and high Curie temperature. 
However, the coercivity of Sm-Fe-based alloys is insufficient for practical application,
so it is necessary to control phases and microstructures to increase the coercivity.
In this work, we modified Sm-Fe-Ti-based powders by changing alloy composition 
and optimizing preparation conditions, and investigated the consequent changes in 
magnetic properties, phases, and microstructures.
The Sm-Fe-Ti-based powders were prepared by induction melting and ball-milling. 
The largest coercivity we obtained is 606 kA/m for Sm-rich compositional fine 
powders, which is presumably related to the SmFe3-like phases.

Achievement of high coercivity in Sm-Fe-Ti-based powders

Development of Composition and Powder Fabrication for the Additive Manufacturing of (Pr,Nd)-Fe-Cu-B Permanent Magnets

NdFeB-based magnets are key components widely used in the automotive industry, electronics, energy conversion systems and acoustic products. Owing to the unstable supply and high cost of less abundant rare earths (e.g. Dy and to some extent Nd), it is important to reduce cost while maintaining performance. In order to address this problem, the partial replacement of Nd with La and Ce, which are cheaper and more abundant than Nd, is actively being pursued. In this work, a triple target geometry is used for a high throughput study of NdLaCeFeB films. By using movable target shields, a set of films with different composition gradients have been deposited and post-annealed under different conditions. 2D composition maps of as-deposited films were made using EDX (Energy Dispersive X-Ray) analysis in an SEM. High throughput magnetic characterisation was carried out using an in-house developed high field scanning MOKE system operated at room temperature[1]. High throughput XRD measurements were also made to investigate changes of phase and texture. More detailed magnetic characterisation of certain sample parts was carried out using SQUID-VSM. Also, machine learning based data analysis enabled us to show the correlation among compositions, microstructures and magnetic properties. In this work we demonstrate the potential offered by the combinational high throughput approach to the development of NdLaCeFeB films and reveal the influence of La and Ce content on the magnetic and structural properties of such films.

A High Throughput Study of compositionally graded NdLaCeFeB Films

Searching for perfect defects challenging the Brown's paradox in permanent magnetism

Preparation of R-Fe alloy nanopowder by Induction thermal plasma process

The Effects of Zr + Fe2B additions on NdFeB-type Material during the Hydrogen Ductilisation Process (HyDP)

Permanent magnets are a key element of a sustainable and energy-efficient economy. While their use is becoming increasingly popular in energy-related applications, the current supply of neodymium for Nd-Fe-B magnets raises severe environmental and resource-security concerns. In response, projects like SUSMAGPRO undertake efforts to investigate recycling technologies.
As part of the SUSMAGPRO project, we assessed the environmental profile of hydrogen-based processing of magnetic scrap (HPMS) at lab scale. We performed a life cycle assessment comparing the production of sintered magnets made of Nd-Fe-B recovered via HPMS with the production using mined Nd. The assessment included the comparison of three coating alternatives: Ni-Cu-Ni, Ni and epoxy resin. The results indicate a better environmental performance of the recycled alternative compared to the primary alternative in all the evaluated impact categories. The advantage of the HPMS route is mainly driven by a lower use of energy. The coating of the recycled Nd-Fe-B magnets turned out to be the largest contributor to their environmental burden in several impact categories.
Nickel, Ni-Cu-Ni and epoxy coatings are just an option among a plethora of alternatives. From a recycling perspective, the evaluated metallic coatings are preferred because these allow an easier recycling than epoxy coatings. With this contribution, we take a step forward in answering the next question: How will the future supply chain of Nd magnets manage the trade-off between a higher environmental impact during manufacture and an increased recyclability?

Sm-Co hard magnetic alloy nanopowder prepared by induction thermal plasma process

Next from REPM 2021: The 26th International Workshop on Rare-Earth and Future Permanent Magnets and their Applications

Roles of local texture in crystallinity and magnetic properties of highly coercive Sm-Fe-N fine powder by jet-milling

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