Presentation Information
[O8-2]Rapid quenching of nanocrystalline Nd-Fe-B materials for high performance magnets from recycled feedstock in industrial scale: Challenges and opportunities
*Karsten Rachut1, David Bender1, Alexander Buckow1, Iliya A. Radulov2, Jürgen Gassmann2 (1. Heraeus Remloy (Germany), 2. Fraunhofer Research Institution for Materials Recycling and Resource Strategies IWKS (Germany))
Keywords:
Nd-Fe-B,Recycling,Rapid Quenching,Melt Spinning
Nd-Fe-B magnets produce the most efficient electrical machines and continue to find new applications in clean energy technologies. This growing demand for rare earth magnets has led to supply chain concerns for users of these critical materials. Some forecasts predict a global supply gap in the short term. European automotive and electronics manufacturers heavily rely on the import of these materials from Asia. As a result, the European Union has initiated the Critical Raw Materials Act to mitigate the supply gap and limit the EU’s dependence on critical material imports.
One solution to contribute to that process is recycling of end-of-life Nd-Fe-B magnets. As a part of the Heraeus Group, Remloy is one of the most advanced European recyclers for Nd-Fe-B magnets with a midterm planned capacity >1000 tons / year. Heraeus Remloy purchases, analyses, sorts and processes end-of-life magnets and production scrap into valuable high-performance nanocrystalline magnetic materials using the melt-spinning technology. Throughout this process several challenges and opportunities have become apparent. The inhomogeneous end-of-life magnet feedstock generally consists of sintered Nd-Fe-B magnets with varying alloy compositions, oxygen and carbon contents, coatings and physical masses. Turning this inhomogeneous feedstock into a robust alloy for the melt-spinning process is discussed in this contribution. Consequently, new alloys for the rapid quenching route are being developed and offer opportunities for bonded magnet and hot formed magnet users. It is shown that recycled melt-spun material for bonded magnets can compete with primary magnetic powders, while offering a significantly lower CO2- footprint and environmental impact. Typical, mid-grade recycled melt-spun powders with a remanence Br = 840 mT, a coercivity HcJ = 755 kA/m and a maximum energy product (BH)max = 115 kJ/m3 can be repeatedly produced at the industrial plant in Bitterfeld, Germany.
Yet more Nd-Fe-B recycling activities and enterprises will be required to advance this circular economy in the future. Early results have indicated that recycled melt-spun powders can be used for hot-pressed and hot-deformed magnets, without additional primary heavy rare earths, and thus compete with Dy / Tb - containing sintered Nd-Fe-B magnets for many automotive applications. The nanocrystalline structure of rapidly quenched Nd-Fe-B can be leveraged to mitigate the need for these high-cost heavy rare earth elements. Heraeus produced powders have been hot formed into magnets with remanences of 1.25 T while having coercivities in the range of 1400 kA/m, which has shown the promising potential for this processing route.
One solution to contribute to that process is recycling of end-of-life Nd-Fe-B magnets. As a part of the Heraeus Group, Remloy is one of the most advanced European recyclers for Nd-Fe-B magnets with a midterm planned capacity >1000 tons / year. Heraeus Remloy purchases, analyses, sorts and processes end-of-life magnets and production scrap into valuable high-performance nanocrystalline magnetic materials using the melt-spinning technology. Throughout this process several challenges and opportunities have become apparent. The inhomogeneous end-of-life magnet feedstock generally consists of sintered Nd-Fe-B magnets with varying alloy compositions, oxygen and carbon contents, coatings and physical masses. Turning this inhomogeneous feedstock into a robust alloy for the melt-spinning process is discussed in this contribution. Consequently, new alloys for the rapid quenching route are being developed and offer opportunities for bonded magnet and hot formed magnet users. It is shown that recycled melt-spun material for bonded magnets can compete with primary magnetic powders, while offering a significantly lower CO2- footprint and environmental impact. Typical, mid-grade recycled melt-spun powders with a remanence Br = 840 mT, a coercivity HcJ = 755 kA/m and a maximum energy product (BH)max = 115 kJ/m3 can be repeatedly produced at the industrial plant in Bitterfeld, Germany.
Yet more Nd-Fe-B recycling activities and enterprises will be required to advance this circular economy in the future. Early results have indicated that recycled melt-spun powders can be used for hot-pressed and hot-deformed magnets, without additional primary heavy rare earths, and thus compete with Dy / Tb - containing sintered Nd-Fe-B magnets for many automotive applications. The nanocrystalline structure of rapidly quenched Nd-Fe-B can be leveraged to mitigate the need for these high-cost heavy rare earth elements. Heraeus produced powders have been hot formed into magnets with remanences of 1.25 T while having coercivities in the range of 1400 kA/m, which has shown the promising potential for this processing route.
