L10 ordered FeNi alloy is considered as a promising candidate for rare-earth-free and environment-friendly permanent magnet. Highly ordered single-phase L10 FeNi is challenging to synthesize due to its low chemical order-disorder transition temperature. Recently, a nonequilibrium synthetic route utilizing a nitrogen topotactic reaction was considered as a valid approach although the detailed phase transformation mechanism is missing.[1] In this work, we investigated the formation mechanism of the tetragonal FeNiN precursor phase during the nitridation of FeNi nanopowders. [2] 
A low oxygen induction thermal plasma system was applied to synthesize the FeNi nanopowders (NPs). The processed FeNi NPs were annealed under a hydrogen gas flow at 1 L/min for 2 h at 400 °C. Then, the NPs were nitrided at 350 °C under ammonia with gas flowing at 2 L/min for 16 h. The detailed microstructure analysis was performed with an atomic resolution analytical electron microscope JEM ARM200F. 
High-resolution TEM observation reveals intensive nanotwins in the nitrided FeNi NPs which results in a distorted lattice Interestingly Fe segregates at the TBs was confirmed with EDS mapping. Thus, the nanotwins region may provide preferential nucleation sites for the FeNiN product phase in the Fe2Ni2N parent matrix Furthermore, detailed microstructure characterization shown in Fig.1 revealed that the growth of the FeNiN product phase followed a massive transformation with high index irrational orientation relationships and ledgewise growth motion characteristics detected at the FeNiN/Fe2Ni2N migrating interface. Based on the results, we delineated a potential formation route of the FeNiN precursor phase in the FeNi NPs during nitridation. 
**Acknowledgment:** 
This work was partially supported by the project Development of Magnetic Material Technology for High Efficiency Motors which was commissioned by Japan's New Energy and Industrial Technology Development Organization (NEDO). 
**References:** 1) G oto, S. et al. Synthesis of single-phase L10 FeNi magnet powder by nitrogen insertion and topotactic extraction.
Sci Rep 7, 13216, doi:10.1038/s41598 017 135622 (2017). 
2) Wang, J., Hirayama, Y., Liu, Z. et al. Massive transformation in FeNi nanopowders with nanotwin assisted
nitridation. Sci Rep 12, 3679, doi.org/10.1038/s41598-022-07479-8 (2022). 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/7799f041271182e5315509ee10844611.png) 
Fig. 1. ABF-STEM images of nitrided FeNi NPs with terraces/ledges demonstrating the ledgewise growth motion of the FeNiN/Fe2Ni2N interface (a & b). (c) schematizes the representative high-index orientation relationship present in (b).[2]

Nanotwins assisted nitridation in FeNi nanopowders synthesized by induction thermal plasma

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.

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

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

1. Introduction Anisotropic nanocomposite (NC) magnet which utilizes the exchange coupling effect between the hard and soft magnetic phase is attracting a lot of attention as a next-generation permanent magnet [1]. However, the realization of anisotropic NC magnet is still experiencing many difficulties, and its maximum energy product (BHmax) is less than that of a single-phase permanent bulk magnet [2, 3] since its microstructures are not well-controlled in the nanoscale. In order to realize the nanoscale-controlled microstructure with an effective exchange coupling effect, the grain size of the soft magnetic phase needs to be smaller than twice the domain wall width of the hard magnetic phase [4]. In this work, we attempted to prepare the anisotropic bulk NC magnet with the nanoscale-controlled microstructure by using the powder metallurgy process. SmCo5 compound as a hard magnetic phase which has a high anisotropy field [5] and Fe with high saturation magnetization as a soft magnetic phase were chosen as a preliminary work. The precursor needs to satisfy with the following requirements: (1) anisotropic hard magnetic powder, (2) fine soft magnetic powder. In addition to these requirements, the surface oxide of hard and soft magnetic powder should be as thin as possible for effective exchange coupling effect. Therefore, the preparation and handling of the micro-sized SmCo5 and nano-sized Fe powder have been done in low oxygen atmosphere. Using the mixture of these powders, we have synthesized an anisotropic bulk NC magnet and evaluated its microstructure and magnetic properties. 2. Experimental procedure SmCo5 ingot was prepared by the arc-melting process. The ingot was roughly crushed to around 100 μm powder by a blender. SmCo5 powder was more refined by the jet-milling process in a glove box. Fe nanopowder was prepared by the induction thermal plasma process. The detail experimental set up and condition were described elsewhere [6]. The prepared nano-sized Fe powder was handled in a glove box to prevent the oxidation. Then, SmCo5 powder and Fe nanopowder were mixed with as SmCo5-10 wt.% Fe by a homogenizer in heptane. The mixture was magnetically aligned under 2 T at 300 K, then consolidated at 600 °C under 300 MPa by the direct current sintering process. The phase of SmCo5 powder and SmCo5/Fe NC magnet was analyzed by X-ray diffractometer (XRD). Magnetic measurement was carried out by a vibrating sample magnetometer (VSM). The microstructure of the NC magnet was observed by scanning electron microscope (SEM). 3. Results and discussion In the XRD profile, the compound prepared by the arc-melting was single phase of SmCo5. Even after the jet-milling process, the peaks of single phase SmCo5 without oxides were also detected. The peaks of the jet-milled SmCo5 powder were slightly broadened because the particles were damaged by large mechanical energy during the jet-milling. The median particle size (D50) of the jet-milled powder was measured as 2.5 μm. In Fig. 1(a), the black line represents the hysteresis loop measured along an easy direction of magnetically aligned the jet-milled SmCo5 powder. The coercivity of 12.8 kOe was obtained. The magnetizations at 9 T were almost saturated, and its values were measured as 100 emu/g, which is similar with the intrinsic properties of SmCo5 compound [7]. The red line in Fig. 1(a) shows the hysteresis loop measured along an easy direction of magnetically aligned SmCo5-10 wt.% Fe bulk NC magnet. An anisotropic magnetic behavior was clearly confirmed by the magnetic measurement. The magnetization at 9 T was measured about 10 % higher than that of SmCo5 powder because of the addition of 10 wt.% Fe nanopowder, indicating that the SmCo5 and Fe powders were consolidated without a formation of another intermetallic compounds. The XRD profile also showed the peaks of only SmCo5 and Fe. The recoil loop clearly represented a non-linear spring back effect, indicating that the nano-sized Fe powder with negligibly thin oxide film was partially exchange-coupled with anisotropic SmCo5 powder. Another evidence of exchange-coupling is that the remanent magnetization was increased by the exchange-coupled Fe. In consequence, we realized the exchange-coupled anisotropic SmCo5/Fe bulk nanocomposite magnet by the low oxygen powder metallurgy process. This work proposed the strategy to achieve an improved anisotropic bulk NC magnet. Fig. 1(b) shows the cross-sectional image of SmCo5-10 wt.% Fe bulk NC magnet. There are many pores in the magnet, which leads to the reduction of the effective exchange interaction. In order to obtain the more densified magnet, the higher sintering temperature and/or pressure is effective. Moreover, there is a possibility to refine the Fe nanoparticle by controlling the conditions of thermal plasma such as counterflow gas and radial injection of cooling gas [8]. It is expected that the finer Fe nanoparticle could be more effectively exchange-coupled with a hard magnetic phases. 4. Conclusion In this study, SmCo5 powder was prepared by the jet-milling process, and coercivity of 12.8 kOe and magnetization of 100 emu/g were obtained. Fe nanopowder with average particle size of 100 nm, was synthesized by ITP process. The magnetic measurement revealed the anisotropic magnetic behavior of SmCo5/Fe NC magnet.

**References:**

[1] E. F. Kneller and R. Hawig, IEEE Transactions on Magnetics, Vol. 27, p.3588 (1991) [2] M. Ito, K. Majima and H. Nagai, Journal of alloys and compounds, Vol. 329, p.272 (2001). [3] J. Zhang, S. Y. Zhang and B. G. Shen, Journal of Applied Physics, Vol. 89, p.5601 (2001) [4] R. Fischer, T. Leineweber and H. Kronmüller, Physical Review B, Vol. 57, p.10723 (1998). [5] H. Nakamura, Scripta Materialia, Vol. 154, p.273 (2018). [6] Y. Hirayama and K. Takagi, Journal of Alloys and Compounds, Vol. 792, p.594 (2019). [7] S. Liu, Chinese Physics B, Vol. 28, p.017501 (2019) [8] X. Zhang, Z. Liu and T. Watanabe, Chemical Engineering Science, Vol. 230, p.116217 (2020).

**Images:**

![](https://assets.underline.io/uploads/markdown_image/1/image/19f15556270244607e86f5e12726992e.jpg)
Fig. 1. (a) Hysteresis loops measured along an easy direction of magnetically aligned SmCo5 powder (black line) and SmCo5-10 wt.% Fe bulk NC magnet (red line). (b) Cross sectional image of SmCo5-10 wt.% Fe bulk NC magnet.

 Preparation of SmCo5 and Fe magnetic precursor for realizing anisotropic bulk nanocomposite magnet by low oxygen powder metallurgy process

High-performance, high-efficiency motors are indispensable for the development of electric vehicles and the realization of electric aircraft. The key is the development of permanent magnets that can withstand use even at high temperatures. The reported Sm-Fe-based magnet compounds [1-3] have a high Curie temperature, and the values of the magnetic anisotropy field and saturation magnetization are higher or comparable to those of Nd2Fe14B. In this work, we focused on the Induction thermal plasma(ITP) process as a new process for obtaining anisotropic nano-sized powder of these permanent magnet compounds. The ITP process is a physical bottom-up process that can synthesize nano-sized single-crystal powders due to the high quenching effect during the process [4, 5]. When this process can be applied to prepare a fine permanent magnet anisotropic powder of around 100 nm, which is difficult to obtain by the conventional method, can be synthesized, leading that an anisotropic magnet having a large coercive force can be obtained. Therefore, as the first step, we tried to produce nano-sized anisotropic Sm-Fe-N alloy powder and to evaluate the feasibility of preparing the nano-sized powder by the ITP process. The mixed powder of Sm powder (D50 = 18 μm) and Fe powder (particle size about 3 μm, High Purity Chemical Laboratory) was used as a starting powder for the ITP process. The ITP process was performed under the condition of process pressure of 100 kPa. The input power was 6 kW. Since Sm metal powder as a starting material is not commercially available, we prepared micron-sized Sm powder by using a crucible-less skull gas atomizing device (manufactured by Sinfonia Technology Co., Ltd.). Though the ITP process, the obtained nano-sized powder was sealed in a quartz capillary in a glove box, and the crystal structure was evaluated by a powder X-ray diffraction experiment with Aichi Synchrotron BL5S2 without oxidizing the powder. In addition, SEM and STEM were used for microstructure analysis. From the XRD profile, SmFe2 and Sm-Fe with TbCu7-type structure were identified as Sm-Fe alloy phases. From the SEM image, the average particle size of the SmFe alloy was about 100 nm. The Sm-Fe alloy particles were found to be single crystals by high-resolution STEM observation. In addition, many particles consist of Fe-core/Sm-shell and Fe-core/SmFe-shell were also observed. Combine the results obtained from the XRD measurement and the STEM observation, it was found that the Fe detected by XRD is not the Fe particle but the Fe core in the core-shell structure. This is because the vapor pressure of Sm is more than 10000 times higher than that of Fe, so in the thermal plasma process, Fe nucleates first and then Sm and Fe or Sm agglomerates around the Fe particles. After the nitriding process by the heat treatment at an elevated temperature of 400C in N2 flow for 15min, nitrogen was surely introduced into the Sm-Fe lattice, which is confirmed from the lattice expansion. For the first time in this study, we succeeded in synthesizing Sm-Fe-N anisotropic particles with a particle size of 100 nm or less using the ITP process. Especially, the preparation of the anisotropic particle with TbCu7-type structure will lead to the next generation high-performance permanent magnet.

**References:**

[1] T Iriyama, K Kobayashi, N Imaoka et al., IEEE Trans. Magn., Vol.28, p.2326 (1992) [2] S. Sakurada, A. Tsutai, T. Hirai et al., J. Appl. Phys., Vol.79, p4611 (1996) [3] Y. Hirayama, Y.K. Takahashi, S. Hirosawa et al., Scr. Mater., Vol.138, p.62 (2017) [4] Y. Hirayama and K. Takagi, J. Alloys. Compd., Vol.792, p.594 (2019) [5] Y. Hirayama, M. Shigeta, Z. Liu et al., Available at http://dx.doi.org/10.2139/ssrn.3692994

**Images:**

 Nano-sized anisotropic Sm-Fe-N particle preparation by induction thermal process

KOB: Hard Magnetic Materials IV: Rare-Earth Free Hard Magnetic Materials

technical paper

#### Welcome to the 67th Annual Conference on Magnetism and Magnetic Materials, MMM 2022!

The Conference was held from October 31 to November 4 and offers both in-person and on-demand content.

MMM 2022 is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a tutorial, and several special sessions. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

<iframe width="560" height="315" src="https://s3.amazonaws.com/pf-user-files-01/u-59356/uploads/2022-11-02/un13zp7/MMM%20Welcome%20Video%20v5.mp4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

For tickets to the event, please register at the following link: https://magnetism.org/registration

Please register for the MMM 2022 conference to join the event.

MMM 2022

This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

**Click 'See All' on the righthand side of the page to expand the view and see all of the posters. **

**Session Chair:**
 Alex Aubert

Poster Session

poster

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.

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

*Session Co-Chair: Alberto Bollero, IMDEA Nanoscience*

*Session Co-Chair: Kinjal Gandha, Iowa State University*

These on-demand presentations are available to view at your leisure.

JW: RE-based and RE-free Permanent Magnets

INTERMAG 2021 Welcome Video



	
<figure class="video_container">
 <iframe src="https://screencast-o-matic.com/player/crflqFVnUpZ?v=6&ff=1&title=0&controls=1" width=640 height=360 frameborder="0" allowfullscreen="true"> </iframe>
</figure>

Want to buy a ticket? 

Register for INTERMAG 2021 here

[![](https://assets.underline.io/uploads/markdown_image/1/image/17ce76e7960db633258024eef8d6da7f.png)](https://intermag.org/register)

Got your ticket, but still can’t access the event?

Contact us and our team will look into it.

Yusuke Hirayama

5

13

SHORT BIO

Presentations

Nanotwins assisted nitridation in FeNi nanopowders synthesized by induction thermal plasma

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

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

Preparation of SmCo5 and Fe magnetic precursor for realizing anisotropic bulk nanocomposite magnet by low oxygen powder metallurgy process

Nano-sized anisotropic Sm-Fe-N particle preparation by induction thermal process

Stay up to date with the latest Underline news!

PRESENTATIONS

CONFERENCES

COMPANY

RESOURCES