Bell Telephone Laboratories

At&t Bell Laboratories

At&t Technologies, Inc.

Sungho Jin

Thomas H Tiefel

Gilbert Y Chin

Richard C Sherwood

Jack H Wernick

John T Plewes

Chester M Bordelon

Bud Caesar Wonsiewicz

Chester M Boredelon

Disclosed are magnetically soft ferritic multiphase Fe-Cr-Ni alloys containing at least about 82 weight percent Fe, between about 3 and about 10 weight percent Cr, and between about 2 and about 8 weight percent Ni, a method for producing such alloys, and devices comprising such an alloy body. The method comprises a low-temperature anneal in the (.alpha.+.gamma.) region of the Fe-Cr-Ni phase diagram. Inventive alloys typically have a coercive force H.sub.c no more than about 3.0 Oe, preferably no more than about 2.0 Oe, a maximum permeability .mu..sub.m of at least about 1500 G/Oe, preferably at least about 2500 G/Oe, and contain at least about 5 volume percent non-.alpha.-phase material, typically .alpha.'- and .gamma.-phase material. Inventive alloys typically also have yield strength to 0.2% offset of at least about 26.10.sup.7 Pa (40.10.sup.3 psi), elongation to fracture of at least about 15%, good formability and rust resistance. Alloys according to the invention can advantageously be used in devices comprising a magnetically soft body, for instance, in electro-acoustic transducers, e.g., in telephone receivers, recording heads, pole pieces, and armatures.

Magnetically soft ferritic Fe-Cr-Ni alloys

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B-H hysteresis loop and high remanent induction. Among alloys having such properties are Co-Fe-V, Co-Fe-Nb, and Co-Fe-Ni-Al-Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe-Mn alloy which contains Mn in a preferred amount in the range of 3-25 weight percent whose remanence B.sub.r (gauss) typically is greater than or equal to 20,000-500.times. (weight percent Mn), and whose squareness B.sub.r /B.sub.s typically is greater than 0.95. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices. Preparation of alloys of the invention may be by a treatment of initial deformation, aging, deformation, and final aging.

High remanence iron-manganese alloys for magnetically actuated devices

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B-H hysteresis loop and high remanent induction. Among known alloys having such properties are Co-Fe-V, Co-Fe-Nb, and Co-Fe-Ni-Al-Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe-Cr-Mo alloy which comprises Cr in a preferred amount in the range of 6-26 weight percent and Mo in a preferred amount in the range of 1-12 weight percent. Preparation of alloys of the invention may be a treatment of annealing, deformation, and aging. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices.

Magnetically actuated device comprising a magnetically anisotropic

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B-H hysteresis loop and high remanent induction. Among alloys having such properties are Co-Fe-V, Co-Fe-Nb, and Co-Fe-Ni-Al-Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe-Ni or Fe-Ni-Mn alloy which contains Ni in a preferred amount in the range of 6-20 weight percent and Ni in an amount which is less than or equal to 8 weight percent. Remanence B.sub.r (gauss) is greater than or equal to 15,000 gauss; squareness B.sub.r /B.sub.s typically is greater than 0.95. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices. Preparation of alloys of the invention may be by a treatment of producing fine-scale, essentially isotropic, two-phase structure, subsequent uniaxial deformation, and aging to achieve a fine-scale, elongated, and aligned two-phase or multiphase structure.

High-remanence Fe-Ni and Fe-Ni-Mn alloys for magnetically actuated

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B-H hysteresis loop and high remanent induction. Among alloys having such properties are Co-Fe-V, Co-Fe-Nb, and Co-Fe-Ni-Al-Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe-Mo-Ni alloy which comprises Mo in a preferred amount in the range of 2-26 weight percent and Ni in a preferred amount in the range of 0.5-15 weight percent. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices. Preparation of alloys of the invention may be by a treatment of annealing and aging or deformation and aging.

Method for making a high remanence Fe-Mo-Ni magnetic element

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B-H hysteresis loop and high remanent induction. Among known alloys having such properties are Co-Fe-V, Co-Fe-Nb, and Co-Fe-Ni-Al-Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe-Cr-Mo alloy which comprises Cr in a preferred amount in the range of 6-26 weight percent and Mo in a preferred amount in the range of 1-12 weight percent. Preparation of alloys of the invention may be by a treatment of annealing, deformation, and aging. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices.

Method for making a magnetically anisotropic element

Disclosed are magnetically soft ferritic multiphase Fe-Ni alloys having a Ni content in the range of about 4 to about 16 weight percent, devices containing a body fabricated from such alloys, and method for heat treating such body. Appropriate heat treatment comprises a low-temperature anneal in the two-phase (.alpha.+.gamma.) region of the Fe-Ni phase diagram, and typically results in improved magnetic properties. In particular, alloys according to the invention having x weight percent of Ni have a maximum permeability .mu..sub.m at least as large as 1.5[25(16-x).sup.2 ]G/Oe. The alloys typically also have a coercive field H.sub.c at most as large as 0.7[0.65(1+0.6x)]Oe, a saturation induction B.sub.s of at least about 20 kG, a maximum incremental permeability .DELTA..mu., measured with an applied a.c. field of about 0.005 Oe, of at least about 150 G/Oe, and a yield strength to 0.2 percent offset of at least about 40 10.sup.3 psi, with all the material properties measured at room temperature. Alloys according to the invention can advantageously be used in devices comprising a magnetically soft body, for instance in electro-acoustic transducers, e.g., in telephone receivers.

Ferritic Fe-Ni magnetic alloys

To provide for an inexpensive magnet alloy, isotropic and nearly isotropic permanent magnet properties are developed in Fe-Mo-Ni alloys. Manufacture may be by a method which comprises steps of annealing, optional deforming by a limited amount, and aging. Typical magnetic properties of alloys of the invention are a coercive force in the range of 50-500 oersted, a magnetic remanence in the range of 7000-14000 gauss, and a magnetic squareness ratio of less than 0.9. Alloys of the invention are highly ductile even after plastic deformation, they are readily bonded to aluminum supports (as used, e.g., in the manufacture of twistor memories), and they are readily etched by etchants which leave aluminum unaffected.

Isotropic and nearly isotropic permanent magnet alloys

Magnetically actuated device comprising an Fe-Mo-Ni magnetic element

Magnetically actuated devices such as, e.g., switches and synchronizers typically comprise a magnetically semihard component having a square B--H hysteresis loop and high remanent induction. Among alloys having such properties are Co--Fe--V, Co--Fe--Nb, and Co--Fe--Ni--Al--Ti alloys which, however, contain undesirably large amounts of cobalt. According to the invention, devices are equipped with a magnetically semihard, high-remanence Fe--Mo--Ni alloy which comprises Mo in a preferred amount in the range of 2-26 weight percent and Ni in a preferred amount in the range of 0.5-15 weight percent. Magnets made from alloys of the invention may be shaped, e.g., by cold drawing, rolling, bending, or flattening and may be used in devices such as, e.g., electrical contact switches, hysteresis motors, and other magnetically actuated devices. Preparation of alloys of the invention may be by a treatment of annealing and aging or deformation and aging.

High remanence Fe-Mo-Ni alloys for magnetically actuated devices

To provide for an inexpensive magnet alloy, isotropic and nearly isotropic permanent magnet properties are developed in Fe-Mo-Ni alloys. Manufacture may be by a method which comprises steps of annealing, optional deforming by a limited amount, and aging. Typical magnetic properties of alloys of the invention are a coercive force in the range of 50-500 oersted, a magnetic remanence in the range of 7000-14,000 gauss, and a magnetic squareness ratio of less than 0.9. Alloys of the invention are highly ductile even after plastic deformation, they are readily bonded to aluminum supports (as used, e.g., in the manufacture of twistor memories), and they are readily etched by etchants which leave aluminum unaffected.

Magnetically anisotropic alloys for magnetically actuated devices

Fine-grained Fe-Cr-Co magnetic alloys are disclosed which have desirable magnetic properties such as, in particular, a coercive force in the range of 300-600 Oersted, a remanence in the range of 8000-13000 Gauss, and a maximum energy product in the range of 1-6 MGOe. Disclosed alloys consist essentially of 25-29 weight percent Cr, 7-12 weight percent Co, and remainder iron; processing of disclosed alloys may typically include low-temperature solution annealing, cold shaping, and an aging heat treatment. Disclosed magnetic alloys may be used, e.g., in the manufacture of ringers, relays, and electro-acoustic transducers.

Fe-Cr-Co Permanent magnet alloy and alloy processing

Magnetic alloys are disclosed having an anisotropic magnetic structure produced by thermomechanical treatment in the absence of a magnetic field. Disclosed treatment calls for developing magnetic particles in an alloy by cooling such alloy in a controlled fashion from a first temperature at which the alloy is in a predominantly single phase state to a second temperature at which the alloy is in a multi-phase state. Treatment further calls for deforming the alloy, resulting in cross-sectional area reduction of at least 30 percent (corresponding to elongation of magnetic particles by a factor of at least 1.7). Disclosed treatment leads to desirable magnetic properties, e.g., in Cu-Ni-Fe, Cu-Ni-Co, Fe-Al-Ni, Fe-Al-Ni-Co, and Fe-Cr-Co alloys. For example, in the case of Fe-Cr-Co, alloy properties such as remanence-to-saturation squareness ratio in excess of 0.90 and maximum energy product in the range of 0.6-8.0 MGOe are achieved. Disclosed magnetic alloys are suitable for use in the manufacture of telephone ringers, relays, and electromagnetic transducers.

Magnetically anisotropic alloys by deformation processing

A method is disclosed for making a metallic body having desirable magnetic properties. The metallic body is made from an alloy which contains Fe, Cr, and Co and which may also contain one or several additional ferrite forming elements such as, e.g., Zr, Mo, V, Nb, Ta, Ti, Al, Si, or W. According to the disclosed method the alloy is cooled at a rate of at least 60 degrees C. per hour from an initial temperature at which the alloy is in an essentially single phase alpha state to a second temperature which is in a vicinity of 600 degrees C. Subsequently, the alloy is cooled at a second, slower rate to a third temperature which is in the vicinity of 525 degrees C. The disclosed method allows for a relatively broad range of initial temperatures, is relatively insensitive to compositional variations of the alloy, and permits simple reclamation of suboptimally treated parts. As a consequence, the method is particularly suited for large scale industrial production of permanent magnets as may be used, e.g., in relays, ringers, and electro-acoustic transducers.

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Gillette, NJ, United States of America

Sungho Jin