# Successfully demonstrates the world's first sandwich-structured process technology that overcomes the limitations of conventional grain boundary diffusion, enabling uniform performance enhancement throughout even thick magnets.
# A high-performance magnet technology free of heavy rare earth elements reduces heat generation, improving the efficiency of next-generation motors for applications such as electric vehicles and wind power systems.
CHANGWON, South Korea — Korea Institute of Materials Science (KIMS) , led by President Chul-jin Choi, announced that a research team led by Su-Min Kim and Jung-Goo Lee has developed the world's first next-generation magnet manufacturing technology that uniformly enhances magnetic performance throughout thick magnets while reducing heat generation. This technology is expected to significantly improve the efficiency and stability of magnets used in high-power applications such as electric vehicle traction motors. It is also anticipated to enable new applications, including electric ships that require large, high-performance magnets, thereby serving as a key enabling technology for emerging high-value markets.
Neodymium–iron–boron (Nd-Fe-B) magnets, widely used in electric vehicles and wind turbines, are known for their strong magnetic properties. However, as higher power output requires larger and thicker magnets, it becomes increasingly difficult to maintain high coercivity—the ability to retain magnetization under external influences—throughout the entire magnet. In addition, high-speed operation induces eddy currents within the magnet, generating heat that leads to performance degradation and reduced motor efficiency.
Conventionally, heavy rare earth elements have been added to maintain magnetic performance at elevated temperatures. In particular, grain boundary diffusion processes, which involve coating heavy rare earth elements on the magnet surface and allowing them to diffuse inward, have been widely used. However, this approach is limited by its surface-centered diffusion mechanism, making it difficult to achieve sufficient performance improvement in the interior of thick magnets. Moreover, heavy rare earth elements are expensive and subject to supply chain constraints, posing significant industrial challenges.
To address these issues, the research team developed a sandwich-structured grain boundary diffusion and bonding process, in which multiple magnet layers are stacked and then integrated. By applying a low-melting-point light rare earth alloy—specifically praseodymium (Pr)—not only on the surface but also at the interlayer interfaces, the design enables diffusion to initiate from within the magnet as well. As a result, the technology achieves stable coercivity even in thick magnets while ensuring uniform performance throughout the entire structure. In addition, it demonstrates the potential to reduce reliance on expensive heavy rare earth elements through the efficient use of light rare earth materials.
Notably, the technology also addresses heat generation by forming a high-resistivity structure within the magnet, which suppresses eddy current formation. Unlike conventional approaches that require separate processes for magnet segmentation, grain boundary diffusion, and insulating bonding, this method simultaneously enhances coercivity and electrical resistivity through a single grain boundary diffusion process. This integrated approach simplifies manufacturing while improving magnetic, electrical, and structural properties.
The developed technology is expected to be applicable to a wide range of systems, including electric vehicle traction motors, high-efficiency industrial motors, and wind power generators. It is also anticipated to contribute to the domestic production of high-performance magnets and reduce reliance on imports. In particular, reducing heat generation and improving efficiency at the magnet level are expected to enhance overall motor performance and energy efficiency.
"This study demonstrates a breakthrough in simultaneously achieving high coercivity and reduced heat generation in thick magnets," said Su-Min Kim, senior researcher at Korea Institute of Materials Science. "What differentiates this technology is that it integrates coercivity enhancement, resistivity improvement, and structural bonding into a single process."He added, "This technology has strong potential not only for electric vehicle motors but also for applications requiring large, high-performance magnets, such as electric ships, and is expected to evolve into a key materials technology for next-generation motors."
This research was supported by the Materials and Components Technology Development Program of the Ministry of Trade, Industry and Energy. The results were published online on March 18, 2026, in the international journal Scripta Materialia (Impact Factor: 5.6). The research team is currently conducting follow-up studies for practical motor applications.
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