Magnetic alloys

type of magnet

thumb|A "horseshoe magnet" made of Alnico 5, about 1 [[inch high. The metal bar (bottom) is a keeper, which is placed across the poles when the magnet is not in use. This helps to preserve the magnetization.]]

thumb|Strip of permalloy Permalloy () is a nickel–iron magnetic alloy, with about 80% nickel and 20% iron content. Invented in 1914 by physicist Gustav Elmen at Bell Telephone Laboratories, it is notable for its very high magnetic permeability, which makes it useful as a magnetic core material in electrical and electronic equipment, and also in magnetic shielding to block magnetic fields. Commercial permalloy alloys typically have relative permeability of around 100,000, compared to several thousand for ordinary steel.

Iron alloy optimized for magnetic properties

thumb|Assortment of mu-metal shapes used in electronics, 1951 thumb|Five-layer mu-metal box. Each layer is about 5 mm thick. It reduces the effect of the Earth's magnetic field inside by a factor of 1500.

type of metallic alloy

Supermalloy is an alloy composed of nickel (75%), iron (20%), and molybdenum (5%). It is a high permeability ferromagnetic alloy used in magnetic cores and magnetic shielding in electrical components, such as pulse transformers and ultra-sensitive magnetic amplifiers. It has a resistivity of 0.6 Ω·mm2/m (or 6.0 x 10−7Ω·m), an extremely high relative magnetic permeability (approximately ), and a low coercivity. Supermalloy is used in manufacturing components for radio engineering, telephony, and telemechanics instruments.

Cunife is an alloy of copper (Cu), nickel (Ni), iron (Fe), and in some cases cobalt (Co). The alloy has the same linear coefficient of expansion as certain types of glass, and thus makes an ideal material for the lead out wires in light bulbs and thermionic valves. Fernico exhibits a similar property. It is a magnetic alloy and can be used for making magnets.

Bismanol is a magnetic alloy of bismuth and manganese (manganese bismuthide) developed by the US Naval Ordnance Laboratory.

Sendust is a magnetic metal powder that was invented by Hakaru Masumoto at Tohoku Imperial University in Sendai, Japan circa 1936 as an alternative to permalloy in inductor applications for telephone networks. Sendust composition is typically 85% iron, 9% silicon and 6% aluminium. The powder is sintered into cores to manufacture inductors. Sendust cores have high magnetic permeability (up to 140 000), low loss, low coercivity (5 A/m) good temperature stability and saturation flux density up to .

thumb|300px|Fernico pins on the base of a vacuum tube, designed for a tube socket

Alperm (also alfenol or alfer) is a class of alloys comprising 83-90% of iron and 10-17% of aluminium. The most widely used composition is with 16% Al.

Mictomagnetism is a spin system in which various exchange interactions are mixed. It is observed in several kinds of alloys, including Cu–Mn, Fe–Al and Ni–Mn alloys. Cooled in zero magnetic field, these materials have low remanence and coercivity. Cooled in a magnetic field, they have much larger remanence, and the hysteresis loop is shifted in the direction opposite to the field (an effect similar to exchange bias).