Rare earth alloys

type of magnet

thumb|A handful of mischmetal pellets

thumb|Didymium glasses

Terfenol-D, an alloy of the formula (x ≈ 0.3), is a magnetostrictive material. It was initially developed in the 1970s by the Naval Ordnance Laboratory in the United States. The technology for manufacturing the material efficiently was developed in the 1980s at Ames Laboratory under a U.S. Navy-funded program. It is named after terbium, iron (Fe), Naval Ordnance Laboratory (NOL), and the D comes from dysprosium.