Presentation Information
[O2-1]Cost-Effective Manufacturing of Nano-Grain Neo Magnet
*Jun Cui1 (1. Ames National Laboratory (United States of America))
Keywords:
Nanograin,Nd-Fe-B,Cost-effective
High-power-density electric drive motors require permanent magnets with a high energy product, excellent thermal stability, and reduced reliance on critical materials. Nd-Fe-B-based (Neo) sintered magnets are the primary candidates for this type of applications. However, traditional Neo magnets without heavy rare earth elements (HREEs) exhibit significant degradation in magnetic properties above 150°C, a critical threshold for EV motor applications. Achieving stable operation at 200°C often requires more than 10 wt.% HREE when using conventional sintered magnet fabrication techniques and 2% when using the grain boundary diffusion technique. The use of HREE in large quantity poses challenges due to HREE’s scarcity, high cost, and supply chain vulnerabilities. Therefore, the development of HREE-lean or HREE-free high-temperature Neo magnets is of great interest to the EV industry. Nanocrystalline anisotropic Neo magnets offer a promising alternative, as their grain size is comparable to the magnetic domain size, enabling high coercivity without excessive HREE content. However, conventional nanograin magnet fabrication involves a two-step process—hot pressing for densification followed by hot deformation for texturing—which is costly and limited in productivity. In this work, we introduce a novel semi-continuous, near-net-shape fabrication method for nanograin Neo magnets. We demonstrate that cold rolling of hot container sealed with nanograin Neo powders at 780°C with 75% thickness reduction yields nearly fully dense anisotropic magnets with a maximum energy product (BH)max of 40 MGOe at RT and Hcj reaching 5.8 kOe at 180°C. Furthermore, we will discuss the impact of processing conditions on microstructure evolution and magnetic properties, highlighting its potential for scalable production of high-performance Nd-Fe-B magnets with reduced reliance on HREEs.