Korea Institute of Materials Science develops high-performance EV and robot magnets without heavy rare earths

Republished by AIC Engineering. All rights belong to the original publisher; see Source below.

A technology has been developed to manufacture high-performance permanent magnets without using expensive heavy rare earth elements. It is expected to lay the groundwork for the domestic production and localization of permanent magnets, which are essential for advanced industries such as electric vehicles and robots.

The Korea Institute of Materials Science (KIMS) announced on the 23rd that a research team led by Senior Researcher Su-Min Kim, Principal Researcher Tae-Hoon Kim, and Principal Researcher Jeong-Gu Lee from the Nano Materials Research Division has secured a technology that enables the manufacture of high-performance neodymium-iron-boron (Nd-Fe-B) permanent magnets using ultra-fine powders without heavy rare earths.

Permanent magnets are key materials used in a wide range of advanced industrial applications, including drive motors for electric vehicles, robotic joints, and wind power generators. Neodymium-iron-boron permanent magnets, in particular, are widely used because they can generate a strong magnetic field.

For neodymium-iron-boron permanent magnets to operate at high temperatures, as in electric vehicle drive motors, it is crucial to secure high coercivity so that the magnets do not easily lose their magnetization. Coercivity is the ability of a magnet to retain its magnetization even when it is exposed to an external magnetic field in the opposite direction.

To secure sufficient coercivity, heavy rare earth elements such as dysprosium (Dy) and terbium (Tb) usually need to be added to the magnet. However, heavy rare earths are expensive, and their supply chains are concentrated in a few countries, which makes it necessary to develop technologies that can substitute heavy rare earths.

Instead of adding heavy rare earth elements, the research team developed a technology that enhances magnetic performance by refining the grain structure (crystalline particles) of permanent magnets using ultra-fine powders. The smaller the grains, the better the magnet’s ability to retain magnetization. However, when using conventional methods that mechanically crush alloys to reduce powder size, there is a limit to how small the particles can become.

To overcome this, the researchers reduced powder size through a reduction–diffusion (RD) process that synthesizes fine neodymium-iron-boron crystalline particles using rare earth oxides as raw materials. They also developed a new post-treatment technology to solve the powder oxidation issues that occur in conventional RD processes.

Using the newly developed technology, the team succeeded in producing high-purity neodymium-iron-boron ultra-fine powders with a particle size of about 1 μm (micrometer, one-millionth of a meter).

The researchers further developed powder alignment and sintering technologies to turn these ultra-fine neodymium-iron-boron powders into high-performance permanent magnets. As powder size decreases, friction and agglomeration between particles increase, making it difficult to align the powders uniformly in a magnetic field.

The team improved the alignment of the powder and the stability of the compact by coating the powder surface with a lubricant and applying a damped alternating magnetic field whose direction and strength gradually change. They also employed a hydrogen-assisted process to reduce residual carbon originating from the lubricant and solved the problem of coercivity degradation after heat treatment.

Senior Researcher Kim said, “This achievement is significant in that it overcomes the technical limitations in ultra-fine powder synthesis and powder alignment/sintering processes required for manufacturing high-performance neodymium-iron-boron permanent magnets,” adding, “Once process integration and mass-production technologies are established based on this technology that boosts magnet performance without relying on heavy rare earths, it is expected to be applied in advanced industrial fields that require high-performance permanent magnets, such as electric vehicle drive motors and humanoid robots.”

The research results were published on July 14 and September 19 in the international journals Journal of Alloys and Compounds and Chemical Engineering Journal, respectively. Based on the developed technology, the team has filed a total of nine patents.

Source

• DongA Science (2026-10-23)
• Original article: Korea Institute of Materials Science develops high-performance EV and robot magnets without heavy rare earths
• https://www.dongascience.com/en/news/80510