In an international conference held in Pittsburg about forty years ago in 1983, Dr. Masato Sagawa and Dr. John J. Croat recognized each other as fellow neodymium magnet researchers.
What then is the future of the neodymium magnets they created?
The two researchers share their vision of the future along with manufacturers and users of the permanent magnets.

Sagawa :　It was quite natural as both of us carried out research on RE-Fe (rare earth and iron) magnets when the need for them was increasing.
I think there could have even been three or four researchers publishing at the same time…

Croat :　Actually, after majoring in chemistry at university, I never planned to do research in metallurgy, particularly rare earths. I think it was lucky that I made that choice, as both Dr.
Sagawa and I brought big changes to society with neodymium magnets.

Iriyama :　It wasn’t until 2010 that we started full scale development of sintered neodymium magnets.
Dr. Sagawa established the PLP (Press-less Process) method in his company and we started mass production. I originally doubted that the PLP method would work as production always required a press. However, when I tried the method, it produced a magnet with a higher performance than conventional ones and only required small amounts of heavy rare earths. Still, my assumption was that, although it worked fine in a small-scale experiment, mass production would be difficult. Therefore, we were very happy when we managed to establish conditions for mass production after more than a year of effort.

Une :　One feature of the PLP production method is that it can reduce the crystallite dimensions in low-oxygen conditions. Other manufacturers knew this but were unable to commercialize the technology.
However, Dr. Sagawa and the Daido Steel Group established a successful mass production method, and found that they could produce a very high-performance magnet by applying grain boundary diffusion technology to increase the magnet coercivity using only small amounts of rare earths.
We are now further developing these technologies.

Sagawa :　Well, for example, I have never heard of researchers in the world of superconductivity studying the production method of superconductors.
They receive the Nobel Prize and that’s it (laugh).
That’s fine with superconductivity research, but in sintered magnet research, it does not make sense unless we develop both the magnets themselves and the production method at the same time.
The reason why universities and academia tend not to conduct research into sintered magnets, although they do study hot-deformed magnets, is due to the difficult and danger of sintering production. I think that my research is possible because it is carried out within a manufacturing company.

Croat :　In my case, my research was at the time when demands for neodymium ring magnets and spindle motors for hard disk drives had rapidly expanded due to the spread of personal computers.
My neodymium magnets were originally produced in small quantities in a laboratory and I provided them as samples to various companies, particularly small motor manufacturers in Japan. Then I moved to Delco Remy to help commercialization of the magnets, where I faced a struggle with the production processes.

Croat :　In hybrid vehicles (HVs) and electric vehicles (EVs), the engines that provide the driving force are being replaced by motors. Neodymium magnets play a key role in the motors that we are using now.
Particularly in HVs, we need to fit a motor and a generator into the space that was occupied by the engine and the number of components is increasing. To minimize their size, we use neodymium magnets. To make HVs widely available, we have to reduce costs. To achieve this, because of their compactness and high performance, our current choice is solely neodymium magnets.

Croat :　That’s right. That was the mission of the General Motors Magnetic Materials Group at that time. However, the demands for use in other electronic devices surpassed their full-fledged use in automobiles. That must have been a contributory factor in General Motors eventually selling their Magnetic Materials division.

Yamanaka :　Today, a number of neodymium magnets are used in a single automobile. Our mission in this situation is to reduce the quantity of magnets used in a car and create a motor with less resource usage. Ideally speaking, we would be happy if we could use magnets whose material procurement was not influenced by global affairs.
The performance of the magnets developed with great efforts by Dr. Sagawa and Dr. Croat is being further improved. We feel a responsibility to fully utilize this performance.

Iriyama :　To employ a neodymium magnet free from heavy rare earths for the first time in Honda’s HV, we who developed the magnet worked closely with Honda, who were developing the motor. A magnet free from heavy rare earths has a lower thermal durability, so Honda designed the motor to suit the thermal conditions to achieve commercialization. It was a great accomplishment to reduce resource risks.
To prepare for a future situation that may require us to further reduce the use of heavy rare earths, as well as neodymium itself, magnet manufacturers like us and user corporations must maintain close communications. We hope that both the magnet manufacturers and the users can express their ideas freely from the design stage so that we can align our directions to jointly develop high-performance and low-cost magnets with low resource risks.

Croat :　How is the bonded magnet that I developed used now?

Iriyama :　They are used in motors and sensors in automobiles. It is said that about 100 to 200 motors and sensors are used in a car, and most of the magnets used in them have been low-cost ferrite magnets. Bonded neodymium magnets are expensive as a magnet; however, they can be shaped into a component and thereby reduce both costs and component size. Probably some 20 of the in-vehicle magnets are bonded magnets, I believe.

Croat :　We constantly have to keep in mind the issues with the supply of rare earths. The Mountain Pass Mine in California where we used to mine was once the world’s largest, but it was forced to close after it succumbed to competition. I think it requires a strategic approach at the national level to address the geopolitical risks.

Sagawa :　The neodymium magnet is irrefutably the most powerful, so the only thing we can do is to eliminate manufacturing losses completely by refining the process to the limit. We have already established a production method for magnets that are free from heavy rare earth elements and laminated magnets that are free from eddy-current losses. We need to make progress with these developments to achieve mass production.

Une :　As motors with different mechanisms are being developed, we would like to know the requirement at the earliest possible stage to incorporate them in the magnet’s development.
We also proceed with development that takes account of predicted needs. Led by academia, the magnet industry is seeking ways to use AI to accelerate research and we hope it will speed up our development.

Yamanaka :　In terms of design, there is a limit to minimizing the use of magnets. As Dr. Sagawa mentioned, the key lies in collaboration to streamline the production process. As a result, the shapes and sizes of magnets will be limited and that is where we, the designers, are focusing our efforts.
Even with bonded magnets, there is a limit to their minimization, so we are currently working on a recyclable design so that they can be retrieved and collected. We know that we always ask Daido Steel for the impossible!

Sagawa :　Even if we find a good compound, there is a big hurdle before we can make it into a magnet.
We know when we discover the compound whether it has the qualities to overcome the hurdle. There are compounds that can just about exceed the neodymium magnet; however, none of them have metallurgical capabilities that are sufficient to allow us to stabilize the magnetic properties with an improved compound and cellular structure.

Iriyama :　The neodymium magnet will undoubtedly remain the most powerful magnet. Based on some calculations, the performance values of the neodymium magnet could potentially be much higher. We aim to exploit this potential as much as possible and continue to make efforts to reduce manufacturing losses.
When we think about resources and the global environment, as neodymium continues to be mined, the relative amount of rare earth elements remaining becomes greater. We think it is possible to create magnets with reasonable performance using these remaining rare earth elements. One calculation is said to show that recycling neodymium magnets can reduce CO2 emissions by half compared to mining fresh materials. We plan to continue our basic research in light of recycling technologies.

Yamanaka :　At the moment, it is impossible to design an automobile without neodymium magnets.
However, we are hoping to develop technologies to utilize other magnets in combination. And we would like to make use of recycling technologies to develop a carbon-neutral car.

Iriyama :　I am researching the samarium-iron-nitride magnet, an alternative rare earth magnet to the neodymium magnet. For its production, we use the rapid solidification process that Dr. Croat developed. The rapid solidification process was so difficult that it could not be applied to mass production. This dramatically improved following the effective advice that Dr. Croat gave us six years ago. Now we are working to expand the business.
We heard that Dr. Croat faced years of difficulty before he achieved mass production, and he did not hesitate to share his insights with us. We would like to thank Dr. Croat for his generous attitude.

Croat :　I am happy to hear that. It has been a while since I left the research frontline, but working as a materials scientist was always worthwhile and interesting. I would recommend it to young people who want to become scientists. It is an occupation that can bring significant changes to society.

The talk session took place the day after the award ceremony.