Developing Substitutes: Rare Earth Magnets and Dysprosium Resource Criticality

Beginning with the discovery of high-anisotropy Cobalt-based permanent magnet materials by Strnat et al over 50 years ago [1], the materials science community has been continually searching for new high-performance magnets, which are exemplified by the 1982 discovery by Sagawa et al of the Nd 2 Fe 14 B material. This material has been optimized to performance levels, measured as energy product, as high as 55 MG-Oe, although more commonly used grades typically fall in the 40-48 MG-Oe range.

As a material, Nd 2 Fe 14 B suffers from a lower-than-optimal ordering point, at 312 C, which typically causes its coercivity to be dramatically reduced at temperatures above approximately 100 C. Traditionally this difficulty has been rectified via the addition of the heavy rare earth Dysprosium, which increases coercivity significantly although it also reduces energy products. Strenuous efforts worldwide, through grain boundary engineering, have succeeded in reducing the amounts of Dysprosium necessary for this purpose, although not eliminating it entirely. This current necessity of Dysprosium usage poses a major supply risk to the United States given the present lack of Dysprosium in U.S. resources.

In this talk I will present U.S. Department of Energy-funded Critical Materials Innovation Hub efforts to address this risk. These include NdFeB magnet processing efforts to increase coercivities appreciably from current levels, the development of substitution materials based on Nd 2 Fe 14 B and its sister rare earth materials, processing work based on the SmFeN permanent magnet material [3], and finally efforts aimed at developing entirely new permanent magnet materials.