US 12,272,471 B2
Fine grain structures for tough rare earth permanent magnets
Baozhi Cui, Ames, IA (US); and Jun Cui, Ames, IA (US)
Assigned to Iowa State University Research Foundation, Inc., Ames, IA (US)
Filed by Iowa State University Research Foundation, Inc., Ames, IA (US)
Filed on Oct. 19, 2020, as Appl. No. 16/974,145.
Claims priority of provisional application 62/974,009, filed on Nov. 6, 2019.
Prior Publication US 2021/0134497 A1, May 6, 2021
Int. Cl. H01F 1/055 (2006.01); H01F 1/058 (2006.01); H01F 1/059 (2006.01); H01F 7/02 (2006.01); H01F 41/02 (2006.01)
CPC H01F 1/0557 (2013.01) [H01F 1/058 (2013.01); H01F 1/059 (2013.01); H01F 7/02 (2013.01); H01F 41/0253 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A sintered rare earth permanent magnet comprising at least one region comprised of a sintered feedstock blend of rare earth alloy feedstock particles and artificially-added grain-refining submicron feedstock particles having an average particle size of less than 1 micron wherein the sintered feedstock blend provides a refined grain microstructure that includes a rare earth alloy magnet matrix and the artificially-added grain-refining submicron feedstock particles dispersed in the microstructure which has an average refined grain size from about 15 to less than 40 microns, wherein the at least one region having the refined grain microstructure provides the sintered magnet with at least one of mechanical toughness and/or mechanical strength beneficial for inhibiting micro-cracking of the magnet.