PERMALLOY
Permalloy
Permalloy is a nickel-iron magnetic alloy, with about 20% iron and 80% nickel 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.The above text is a snippet from Wikipedia: Permalloy
and as such is available under the Creative Commons Attribution/Share-Alike License.