Mu-metal
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Mu-metal, or μ-metal, is a soft nickel–iron ferromagnetic alloy with very high permeability, which is used for shielding sensitive electronic equipment against static or low-frequency magnetic fields.
Assortment of mu-metal shapes used in electronics, 1951
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.
Mu-metal shields for cathode-ray tubes (CRTs) used in oscilloscopes, from a 1945 electronics magazine
Permalloy
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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 magnet
Mu-metal
…fields. This gives it low hysteresis losses when used in alternating current (AC) magnetic circuits. Other high-permeability nickel–iron alloys such as permalloy have similar magnetic properties; mu-metal's advantage is that it is more ductile, malleable and workable, allowing it to be easily formed into the…
Strip of permalloy