Highlights

• Chinese researchers achieved a 42% increase in magnet coercivity while using only 0.11 wt.% terbium through an innovative multi-component grain boundary diffusion process, reaching 64.36 kOe efficiency per wt.% Tb.
• The breakthrough optimizes terbium distribution throughout the magnet rather than concentrating it wastefully at surfaces, potentially reducing dependence on costly, geopolitically constrained heavy rare earth elements.
• While promising for electric vehicles, wind turbines, and defense applications, the technology remains lab-scale and faces challenges in industrial scaling, commercial geometry testing, and long-term durability validation.

---

A new study led by Shaoqiang Wu (opens in a new tab) of the Ningbo Institute of Materials Technology and Engineering (opens in a new tab) (part of the Chinese Academy of Sciences), in collaboration with researchers from the Zhejiang University of Technology (opens in a new tab), Ningbo University of Technology, and industry partner Ningbo Zhaobao Magnet Co., Ltd. (opens in a new tab), reports a notable advance in reducing reliance on scarce heavy rare earth elements (HREs) like terbium (Tb). Published in the Journal of Alloys and Compounds (April 2026, in press), the team demonstrates a ~42% increase in coercivity—a key measure of magnet durability—while using just 0.11 wt.% Tb. For lay readers: this means stronger, more heat-resistant magnets using far less of the most expensive and geopolitically constrained materials, critical for electric vehicles, wind turbines, and defense systems.

Why This Matters: The Heavy Rare Earth Constraint

Modern Nd-Fe-B magnets underpin electrification. But at high temperatures, they risk demagnetization. Manufacturers typically add Tb or dysprosium (Dy) to stabilize performance—materials that are scarce, costly, and heavily controlled by China. The core challenge: boost performance without overconsuming HREs.

StudyMethod: Engineering the Grain Boundary

The team applied grain boundary diffusion (GBD)—coating magnets with a rare-earth-containing film and heat-treating them so that elements diffuse along microscopic grain boundaries.

So instead of high-Tb sources, they engineered a multi-component thin film (Tb–Pr–Nd–Al–Cu–Zn). By varying annealing times (8, 12, 16 hours), they optimized how these distribute inside the magnet, balancing surface concentration and deep penetration.

Key Findings: High Efficiency, Low Terbium

• Coercivity increased from 16.72 → 23.80 kOe(~42%)
• Optimal performance at 12-hour annealing
• HRE utilization efficiency reached ~64.36 kOe per wt.% Tb
• Microstructure revealed:
  • Thin Tb-rich “shells” around grains (not excessively thick)
  • Deep, continuous grain boundary phases (GBP) enabling stability

Translation: rather than concentrating terbium wastefully at the surface, the process distributes it more effectively throughout the magnet—more performance per atom.

What’s New—and Why It Matters

This work reinforces a critical shift: performance gains can come from microstructural design, not just material intensity.

If scalable, implications include:

• Lower dependence on Chinese-controlled heavy rare earth supply
• Reduced magnet production costs
• Improved high-temperature performance in EVs, wind, and defense

Limitations and Open Questions

• Lab-scale validation only—not yet industrialized
• Tested on 6 mm magnets, not full commercial geometries
• Thin-film diffusion at scale remains technically challenging
• Long-term durability and operational stress performance are unproven

REEx Take: Real Progress—But Not Yet a Supply Chain Breakthrough

This is a meaningful materials innovation, but not a substitute for industrial capacity. It shows how engineering can stretch scarce resources, yet the structural gap remains: China dominates separation, refining, and magnet manufacturing.

Shaoqiang Wu, Ningbo Institute of Materials Technology and Engineering

Source: ResearchGate

What Comes Next?

• Scale to industrial magnet production
• Integrate into non-China supply chains
• Validate under real-world operating conditions

In the REEx Great Powers Era 2.0, this advantage goes not just to resource holders, but to those who optimize, engineer, and industrialize their use.

Citation: Wu, S. et al. (2026). Achieving high coercivity enhancement in sintered Nd-Fe-B magnets with minimal heavy rare earth usage via Tb-Pr-Nd-Al-Cu-Zn multi-component grain boundary diffusion. Journal of Alloys and Compounds. DOI: 10.1016/j.jallcom.2026.188113.

Affiliations: Ningbo Institute of Materials Technology and Engineering (CAS); Zhejiang University of Technology; Ningbo University of Technology; Ningbo Zhaobao Magnet Co., Ltd.