The U.S. Department of Energy’s Ames Laboratory, Ames, Iowa, reports that ASM Fellow Karl A. Gschneidner and a team of researchers have developed a low-cost cerium-cobalt alloy that can be added to neodymium-iron-boron to improve magnetic properties in rare-earth magnets. The new alloy eliminates the need for dysprosium, one of the scarcest and most costly rare earth elements.
The result, an alloy of neodymium, iron, and boron co-doped with cerium and cobalt, is a less expensive material with properties that are competitive with traditional sintered magnets containing dysprosium. The materials are at least 20 to 40% cheaper than the dysprosium-containing magnets.
Experiments demonstrate that the cerium-containing alloy’s intrinsic coercivity — the ability of a magnetic material to resist demagnetization — far exceeds that of dysprosium-containing magnets at high temperatures.
“We found that this material works better than anything out there at temperatures above 150°C,” says Dr. Gschneidner. “It’s an important consideration for high-temperature applications.”
Previous attempts to use cerium in rare-earth magnets failed because it reduced the Curie temperature, above which an alloy loses its permanent magnet properties. The research team discovered that co-doping with cobalt allowed cerium to substitute for dysprosium without losing magnetic properties.
Finding a comparable substitute material is key to reducing manufacturing reliance on dysprosium, because current demand far outpaces mining and recycling sources.
The research was supported by the U.S. Department of Energy’s ARPA-E REACT program (Advanced Research Projects Agency-Energy-Rare Earth Alternatives in Critical Technologies) which develops cost-effective alternatives to rare earths.
