Permalloy is the term for a nickel iron magnetic alloy. Generically, it refers to an alloy with about 20% iron and 80% nickel content. Permalloy has a high magnetic permeability, low coercivity, near zero magnetostriction, and significant anisotropic magnetoresistance. The low magnetostriction is critical for industrial applications, where variable stresses in thin films would otherwise cause a ruinously large variation in magnetic properties. Permalloy's electrical resistivity generally varies within the range of 5% depending on the strength and the direction of an applied magnetic field. Permalloys typically have the face centered cubic cystal structure with a lattice constant of approximately 0.355 nm in the vicinity of a nickel concentration of 80%.

Permalloy is used in transformer laminations and magnetic recording head sensors. In its initial application, Permalloy was wrapped around the insulated copper conductors of telecommunication cables, reducing signal distortion through improved inductive compensation of cable capacitive reactance.

The right conditions for transmitting signals through cables without distortion were first worked out mathematically by Oliver Heaviside. [Bragg, L. "Electricity" (London: G. Bell & Sons, 1943) p. 212-3.] After a prolonged search, Permalloy was discovered in 1914 by Gustav Elmen of Bell Laboratories, who found it had higher permeability than silicon steel. Later, in 1923, he found its permeability could be greatly enhanced by heat treatment.Other compositions of Permalloy are available, designated by a numerical prefix denoting the percentage of nickel in the alloy, for example "45 Permalloy" containing 45% nickel, and 55% iron. "Molybdenum Permalloy" is an alloy of 81% nickel, 17% iron and 2% molybdenum. The latter was invented at Bell Labs in 1940. At the time, when used in long distance copper telephone lines, it allowed a tenfold increase in maximum line working speed. [Bragg, L. "Electricity" (London: G. Bell & Sons, 1943) p. 212-3.]

ee also

* Mu-metal.
* Sendust.
* Supermalloy a material with even higher magnetic permeability


* Richard M. Bozorth, "Ferromagnetism," Wiley-IEEE Press (1993 reissue), ISBN 0-7803-1032-2.
* P. Ciureanu and S. Middelhoek, eds., "Thin Film Resistive Sensors," Institute of Physics Publishing (1992), ISBN 0-7503-0173-2.

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  • permalloy — PERMALLÓY s.n. Aliaj de fier şi nichel folosit la confecţionarea de miezuri magnetice pentru aparate de măsură, la amplificatoare magnetice etc. – Din fr. permalloy, germ. Permalloy. Trimis de oprocopiuc, 12.03.2004. Sursa: DEX 98  PERMALLÓY s.n …   Dicționar Român

  • permalloy — [ pɛrmalɔj; pɛrmalwa ] n. m. • 1925; mot angl., de perm(eable) et alloy « alliage » ♦ Techn. Alliage de fer et de nickel (à 78 % de nickel) d une très grande perméabilité magnétique. permalloy [pɛʀmalɔj; pɛʀmalwa] n. m. ÉTYM. 1925, in Höfler; en… …   Encyclopédie Universelle

  • permalloy — ☆ permalloy [pʉrm΄al′oi, pʉr′mə loi΄ ] n. [ PERM(EABILITY) + ALLOY] any of a series of alloys of iron and nickel with high magnetic permeability: used in magnetic cores, for wrapping underwater cables, etc …   English World dictionary

  • Permalloy — Le permalloy est un alliage magnétique de fer et de nickel, découvert en 1914 par Gustav Elmen des Laboratoires Bell. Il contient généralement 15 % de fer et 80 % de nickel ; sa désignation symbolique selon la norme européenne est… …   Wikipédia en Français

  • Permalloy — Per|mal|loy 〈a. [ loạ] n.; s; unz.〉 aus Nickel u. Eisen bestehende Legierung mit sehr guten magnet. Eigenschaften * * * Permalloy®   [ pəːməlɔɪ, Kurzwort] das, s, weichmagnetische Nickel Eisen Legierung mit etwa 75 80 % Nickel, 15 % Eisen und… …   Universal-Lexikon

  • Permalloy — permalojus statusas T sritis automatika atitikmenys: angl. permalloy vok. Permalloy, n rus. пермаллой, m pranc. permalloy, m …   Automatikos terminų žodynas

  • Permalloy — permalojus statusas T sritis fizika atitikmenys: angl. permalloy vok. Permalloy, n rus. пермаллой, m pranc. permalloy, m …   Fizikos terminų žodynas

  • Permalloy — Allgemeines Name Mu Metall Andere Namen Permalloy Bestandteile Nickel Eisen Legierung mit 81 % Nickel, 19 % Eisen. Andere Mischungsverhältnisse sind auch üblich, wie beispielsweise 80 % Ni, 16 % Fe und 4 % Co. Kurzbeschreibung Feststoff mit hoher …   Deutsch Wikipedia

  • Permalloy — /perrm al oy, perr meuh loy /, Trademark. a brand name for any of a class of alloys of high magnetic permeability, containing from 30 to 90 percent nickel. [1920 25; PERM(ANENT) + ALLOY] * * * ▪ metallurgy       trademark of the Western Electric… …   Universalium

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