M.S. Kesler, M.J Thompson, M.A. Mcquire
Oak Ridge National Laboratory,
United States
Keywords: critical rare earth-free, casting, gap magnet, static magnetic field, EBSD
Summary:
The reliance on critical materials for key technologies poses a national security threat. Of particular concern is the need for critical rare earths for fabricating magnets. Currently, NdFeB-based magnets fill a large application space. Many of these applications do not require the high performance of sintered NdFeB magnets (up to ~54 MGOe), so it is diluted to form a bonded magnet with polymers like nylon. These bonded magnets generally fill a performance regime whose substitute magnet material candidates are referred to as ‘gap’ magnets. As of yet, there are no practical substitute gap magnet materials that can make a significant impact affecting criticality. CeCo-based alloys are a promising critical rare earth-free magnet material system to fill the gap. This material forms a hard magnet upon casting which is an important factor for scalability and, thus, market impact. However, a lack of crystallographic and magnetic alignment in these cast structures limits performance. These magnets appear to display an intrinsic coercivity that’s not linked to the conventional ideas of the emergence of coercivity – magnetic and insulating phases – so improving the coercivity is elusive. Here we discuss the effect of high static magnetic fields, during casting, on CeCo-based magnets with the aims of improving crystallographic/magnetic alignment and coercivity. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.