Production of Anisotropic NdFeB Permanent Magnets with In Situ Magnetic Particle Alignment Using Powder Extrusion

Area of Science:

• Materials Science
• Manufacturing Engineering
• Sustainable Technology

Background:

• Neodymium-iron-boron (NdFeB) permanent magnets are critical for green technologies like wind turbines.
• Recycling end-of-life (Eol) magnets is essential for resource sustainability.
• Powder extrusion molding (PEM) offers a potential route for magnet manufacturing and recycling.

Purpose of the Study:

• To investigate sustainable NdFeB magnet production using powder extrusion molding (PEM) with in situ magnetic alignment.
• To optimize alignment tool geometry and magnetic field parameters for effective particle alignment during extrusion.
• To demonstrate a scalable method for recycling Eol magnets into high-performance anisotropic magnets.

Main Methods:

• Utilized recycled NdFeB powder from Eol wind turbine magnets processed via hydrogen processing of magnetic scrap (HPMS).
• Employed Finite Element Method (FEM) simulations to design and optimize alignment tool geometries and magnetic field parameters.
• Conducted extrusion experiments with varying alignment tool geometries and magnetic field strengths to determine optimal particle alignment configurations.

Main Results:

• Achieved a high degree of particle alignment (Br/Js = 0.95) using PEM with in situ magnetic alignment.
• Demonstrated alignment exceeding that of PEM without external magnetic fields (0.78).
• Successfully produced anisotropic NdFeB permanent magnets without post-machining.

Conclusions:

• Optimized alignment tool geometry and strong magnetic fields during extrusion enable the production of anisotropic NdFeB magnets.
• PEM with in situ magnetic alignment provides a scalable route for permanent magnet recycling and manufacturing.
• This continuous fabrication method allows for near-net-shape strands with customizable cross-sections.