Chinese Researchers Find a One-Step Way to Build Stronger Rare Earth Magnets-While Using Less Terbium

Highlights

• South China University of Technology team combined Al₂O₃ with a Pr-Tb-Al diffusion alloy in a single heat-treatment step to improve sintered Nd-Fe-B magnets.
• Coercivity jumped from 1,190 to 1,782 kA/m using only 0.6 wt% terbium, while corrosion current density dropped from 6.1 to 1.2 μA/cm².
• Higher electrical resistivity reduces eddy current losses, improving energy efficiency in electric motors.
• The study is a laboratory demonstration and does not address production economics, manufacturing scale, or long-term field reliability.
• China's continued advances in magnet engineering highlight a competitive edge beyond raw material control in the global rare earth value chain.

A research team led by Mingpeng Kou at the School of Materials Science and Engineering, South China University of Technology (opens in a new tab) (Guangzhou, China), together with Zuchun Wei, Hongya Yu, Chaochao Zeng, Shiying Chen, and Zhongwu Liu, reports a new manufacturing approach that simultaneously improves three properties of sintered Nd-Fe-B permanent magnets: magnetic strength, electrical efficiency, and corrosion resistance. Published in the Journal of Alloys and Compounds, the researchers combined aluminum oxide (Al₂O₃) with a Pr-Tb-Al grain boundary diffusion alloy in a single heat-treatment step. The result was a substantial increase in coercivity—the magnet's resistance to demagnetization—while using only 0.6 wt% terbium, one of the world's most valuable heavy rare earth elements. The study suggests manufacturers may eventually improve magnet performance while reducing heavy rare earth consumption, although commercial-scale validation remains necessary.

School of Materials Science and Engineering, South China University of Technology

How the Study Worked

The researchers coated commercial Nd-Fe-B magnets with a thin aluminum oxide layer before applying a Pr₆₀Tb₁₅Al₂₅ diffusion alloy and heat-treating the magnets. They then measured changes in magnetic properties, microstructure, electrical resistivity, corrosion behavior, and simulated electromagnetic performance to determine whether one processing step could improve several key performance characteristics simultaneously.

What Changed?

The treated magnets achieved a coercivity increase from 1,190 kA/m to 1,782 kA/m while consuming only 0.6 wt% terbium. Electrical resistivity also increased, helping reduce eddy current losses that waste energy and generate heat in electric motors. Corrosion current density declined from 6.1 to 1.2 μA/cm², suggesting substantially improved durability. According to the authors, these improvements result from continuous grain-boundary phases, thin terbium-rich shells surrounding magnetic grains, and highly resistive rare earth oxides that formed along grain boundaries.

What the Study Does Not Show

This remains a laboratory materials study—not a commercial manufacturing demonstration. The paper does not examine production economics, manufacturing yield, large-scale process control, long-term field reliability, or compatibility with existing high-volume magnet factories. Although the reduction in terbium consumption is noteworthy, the study does not establish whether the process will lower total manufacturing costs or scale economically.

The authors also report no competing financial interests, strengthening confidence that the findings were presented without disclosed commercial conflicts.

Why Investors Should Care

Rare Earth Exchanges believes the broader significance extends beyond terbium savings. This paper illustrates that China continues advancing one of the least appreciated parts of the rare earth value chain: magnet engineering. While Western governments are investing billions in mining, separation, metals, and alloys, Chinese universities and manufacturers continue improving the finished product itself—finding ways to deliver higher performance while using fewer scarce heavy rare earth elements. That distinction matters.

In Great Powers Era 2.0, competitive advantage will increasingly belong not only to those who control critical mineral resources, but also to those who continuously improve the technologies that convert those materials into higher-value products.

Study Authors

Citation: Kou, M., Wei, Z., Yu, H., Zeng, C., Chen, S., & Liu, Z. Simultaneously enhancing the coercivity and service properties of sintered Nd-Fe-B magnets via grain boundary diffusion of Al₂O₃ and Pr-Tb-Al alloy. Journal of Alloys and Compounds, Vol. 1079 (15 August 2026), Article 190113. DOI: 10.1016/j.jallcom.2026.190113.