Price increases affecting industry

2023-08-29

The large price increase of 2011, caused by reductions in China`s exports of rare earth elements, forced the magnet industry to focus on the reduction of heavy rare earth usage. After these reduction developments, many applications still use NdFeB, but no longer need the heavy rare earth elements. The coercivity was enhanced, e.g., by grain size reduction after pulverisation, or by metallurgical additives. Nevertheless, the high operating temperatures of traction machines which can be in the range of 140-200°C, still result in NdFeB magnets needing heavy rare earth elements.

Wind turbine generator production has focused on heavy-rare-earth-free material solutions. However, in order to achieve this, power density has not been maximised, resulting in lower efficiencies.

A quantum step forward in the development of sintered NdFeB was the reduction of heavy rare earths by keeping a large fraction of these elements out of the base material and instead adding them via diffusion into the magnet, after cutting the magnet material into final dimensions. With this so-called grain boundary diffusion (GBD) process, a significant reduction in heavy rare earth usage was possible. Because of the limitations of the diffusion process, which stops when a material gradient gets too small, the dimensions of the final magnets are limited to approximately 6mm in the smallest dimension.

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