What is Rare-earth magnet?
[[File:Ferrofluid Magnet under glass edit.jpg|thumb|right|250px|[[Ferrofluid]] on glass,<ref>Ferrofluid: a liquid that becomes strongly magnetized in the presence of a magnetic field.</ref> with a rare-earth magnet underneath]] '''Rare-earth magnets''' are strong [[permanent magnet]]s made from [[alloy]]s of [[rare earth element]]s.<ref>McCaig, Malcolm 1977. ''Permanent magnets in theory and practice''. New York: Wiley. {{ISBN|0-7273-1604-4}}</ref> Developed in the 1970s and '80s, rare-earth magnets are the strongest type of permanent magnets made. They have much stronger [[magnetic field]]s than other types such as [[ferrite]] or [[alnico]] magnets. There are two types: [[neodymium]] magnets and [[samarium]]-[[cobalt]] magnets. Some rare-earth magnets such as [[Terfenol-D]] are magnetostrictive.<ref>Magnetostrictive materials change their shape or dimensions during the process of magnetization</ref> They also have uses e.g. in [[loudspeaker|speakers]]. Rare earth magnets are extremely [[wikt:brittle|brittle]] and also vulnerable to [[corrosion]], so they are usually [[Plating|plated]] or coated to protect them from breaking, chipping, or crumbling into powder.<ref>Furlani, Edward P. 2001. ''Permanent magnet and electromechanical devices: materials, analysis and applications''. Academic Press Series in Electromagnetism. {{ISBN|0-12-269951-3}}</ref> == References == {{reflist}} [[Category:Alloys]] [[Category:Magnetism]]